JPH11335246A - Neutralizing agent for permanent wave and treatment for perming hair using the same agent - Google Patents

Abstract

(57) [Summary] [Problem] When hair is subjected to permanent wave treatment,
Provided is a permanent wave neutralizing agent which has a small wave-down, a small decrease in elastic modulus and a low wave efficiency due to repeated permanent treatment, and a small deterioration in hair quality. A concentration (anhydrous salt basis) is from 1.5 to 5.4 wt%, and perborate the relationship between pH and the concentration (C ₁₎ is in the range (Figure 1) which satisfies the following inequality Neutralizing agent for permanent wave consisting of sodium aqueous solution. 8.5-0.5C ₁ ≧ pH ₁ ≧ 7.0-0.4C _{1 Using the} above neutralizing agent, the concentration of the aqueous solution of sodium perborate on the hair during the neutralization treatment is 1.0 to 3.3% by weight. %. A method for neutralizing a permanent wave, wherein the treatment is carried out under a condition in which the relationship between% and concentration (C ₂ ) and pH has the following inequality. 8.7-0.8C ₂ ≧ pH ₂ ≧ 7.1-0.6C ₂

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a neutralizing agent for forming a permanent wave and a method for treating a permanent wave of hair using the same. More specifically,
As a neutralizing agent, a permanent wave neutralizing agent (second agent) composed of an aqueous solution of sodium perborate and the above aqueous solution of sodium perborate are used to prevent a decrease in the elastic modulus and wave efficiency of hair due to repeated treatment of permanent wave. The present invention relates to a permanent wave treatment method for hair, which is used.

[0002]

2. Description of the Related Art A permanent wave is applied to hair by the following method. Wrap your hair around a rod,
After applying a reducing agent as a first agent (reducing agent), which is generally a mixture of ammonium thioglycolate, ammonium carbonate, ammonia, etc., the head is covered with a cap and allowed to stand for about 5 to 20 minutes, so that keratin of the hair is obtained. Cutting and plasticizing the disulfide bond (-SS-) of the fiber, giving the hair a deformation along the circumference of the rod,
Thereafter, the first agent is once removed or neutralized with an acidic solution to stop the reduction. At this stage, many of the disulfide groups in the keratin fibers in the hair have been converted to mercapto (SH) groups. Then, for the hair given such a deformation,
A second agent as a neutralizing agent (oxidizing agent) is applied and left for about 15 minutes to oxidize the SH group, restore to a disulfide group and fix hair deformation, and then wash and remove the second agent with water. Dry and finish the work.

What is important for permanents is that the wave efficiency is high (the wave is applied well), the wave after the permanent processing is not easily returned, that is, the wave down is small, and in addition, the hair is damaged due to the repeated permanent processing. As a result, the elasticity is lost, and the wave efficiency is reduced. However, such a decrease in the wave efficiency is small.

[0004] That is, a person who has a permanent hair is generally subjected to permanent treatment repeatedly in a beauty salon every two to three months to maintain the curl deformation. However, since the hair is repeatedly subjected to a reduction and oxidation process, the elasticity of the hair is increased. The above-mentioned problem of minimizing damage to the hair due to the repeated permanent treatment is important because it causes so-called damaged hair that has no waist, is rough, and has low gloss, a decrease in the smoothness and gloss of the hair surface, and the like. However, since each of the above physical properties generally has a tendency to contradict each other, it is very difficult to solve all of them.

[0005]

In particular, the treatment with a neutralizing agent is an oxidation reaction, and the reaction is to oxidize the SH group, convert it to a disulfide group again, and return to the original crosslinked structure. It is difficult to restore the same structure as before, and it is considered that the type of neutralizing agent and the conditions of use have a great effect on the generation of damaged hair with low elasticity. As a neutralizing agent, an aqueous solution of sodium bromate, an aqueous solution of hydrogen peroxide, and the like are known, and in particular, an aqueous solution of sodium bromate is most frequently used in Japan. At present, it cannot be said that it is satisfactory enough.

On the other hand, sodium perborate (NaBO ₃ )
Is hardly used in Japan as a neutralizing agent for the reason that it is easily decomposed in an aqueous solution state, but the inventors of the present invention have noted that sodium perborate is a relatively mild oxidizing agent. As a result of studying a method using sodium perborate, it is possible to reduce the decrease in elasticity and wave efficiency even after repeated permanent treatment, that is, it is an excellent treatment agent for preventing hair damage, It has been found that there is a contradictory relationship that an attempt is made to reduce the decrease in the wave efficiency to increase the wave down.

[0007] In order to solve this problem, the conditions for neutralization treatment with an aqueous solution of sodium perborate were examined. As a result, the concentration and pH of the aqueous solution of sodium perborate were adjusted under specific conditions based on the correlation between the two. When used as a neutralizing agent, it is possible to achieve a reduction in elasticity and prevention of a decrease in wave efficiency, that is, hair damage, as compared with sodium bromate, in a repeated permanent, while maintaining an effect of a certain level or more with respect to wave down. Was found. Further, in the actual neutralization treatment, the neutralizing agent used is diluted by the moisture contained in the hair after the first treatment of the hair, washing with water, wiping and drying, and a change in pH occurs. In consideration of the above, in order to actually treat the hair under the above-mentioned optimum conditions, the optimum concentration and pH of the neutralizing agent to be used were found, and the present invention was reached.

[0008]

That is, the present invention relates to a method for preparing a solution having a concentration (anhydrous salt concentration (in terms of anhydrous salt) of 1.5 to 5.4% by weight,
It is preferably 2.4 to 4.2% by weight, and the concentration and p
The relationship of H is the following inequality 8.5-0.5C ₁ ≧ pH ₁ ≧ 7.0-0.4C ₁ (where C ₁ and pH ₁ are the sodium perborate concentration in the neutralizing agent (weight in terms of anhydrous salt) %) And an aqueous solution of sodium perborate in a range satisfying pH).

In the present invention, the concentration of the sodium perborate aqueous solution (in terms of anhydrous salt) on the hair at the time of the neutralization treatment is 1.0 to 1.0, using the neutralizing agent comprising the above sodium perborate aqueous solution.
A permanent wave neutralization method characterized in that the treatment is carried out under a condition of 3.3% by weight and a relationship between concentration and pH satisfying the following inequality. 8.
_{7-0.8C 2 ≧ pH 2 ≧ 7.1-0.6C 2} ( wherein C ₂
And pH ₂ are the concentration of sodium perborate (weight in terms of anhydrous salt) and pH on the hair during the neutralization treatment)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The neutralizing agent for permanent wave (second agent) in the present invention is an aqueous solution of sodium perborate. As sodium perborate, NaBO ₃ .4H ₂ O (tetrahydrate) and NaBO ₃ .H ₂ O (monohydrate) are commercially available, and any of them can be used.

In the present invention, the aqueous solution of sodium perborate has a concentration and p
H is subjected to a neutralization treatment under specific conditions such that a decrease in elastic modulus and wave efficiency is reduced and there is no risk of wave down, and specific H suitable for neutralization under such conditions. An aqueous solution of sodium perborate having a concentration and a pH is used as a neutralizing agent.

Here, the value of the "20% index" in the hysteresis curve of the stress-strain of the hair was used as an index of the wave-down. In the 20% index, the hair is pulled at a constant speed (5 mm / min) until the strain reaches 20%, and when the strain reaches 20%, the hair is relaxed at the same speed as the tension.
The ratio of the integrated value of the relaxation process and the tensile process of the hysteresis curve obtained here was defined as a 20% index. The reason why the 20% index was used was that it was considered that the wave-down was related to the relaxation of the amorphous portion in the hair, and it was confirmed that the wave-down and the 20% index actually had an inverse correlation.

[0013] Further, hair which has been subjected to permanent treatment by a treatment method which does not cause any problem with wave down in the market is selected, and a 20% index is measured.
5 to 64 are shown. For this reason, a safe area with a small wave-down is set with a 20% index of 64 or more.

The aqueous solution of sodium perborate used as a neutralizing agent for permanent waves in the present invention has a concentration on hair at the time of permanent wave neutralizing treatment of 1 to 3.3% by weight, preferably 1 to 3.3% by weight as an anhydrous salt. 1.6-
Use it after adjusting to 2.8% by weight. When the sodium perborate concentration is low, the wave down becomes large. Also, as described later, in the present invention, the concentration and pH of the aqueous solution of sodium perborate are strictly controlled by a mutual relationship to suppress a decrease in elastic modulus,
It is possible to perform a permanent wave neutralization treatment with good wave efficiency and less wave down, but when the concentration of the sodium perborate aqueous solution on the hair becomes lower than the above lower limit, the pH shifts to the alkaline side. This is not preferred from the viewpoint of hair protection. Conversely, when the concentration is high, the elastic recovery rate decreases, and the hair is damaged by repeated use, which is not preferable.

Further, it is necessary to strictly control the pH of the aqueous solution of sodium perborate. When an aqueous solution of sodium perborate is used, the elastic recovery rate decreases as the pH increases. Therefore, in this respect, a low pH, that is, an acidic side is preferable, but a low pH aqueous solution causes a large wave-down. However, as for pH,
Not all preferred pH ranges exist over all concentrations in the range of 3.3% by weight, and the optimal pH value of the aqueous sodium perborate solution is closely related to the aqueous sodium perborate concentration. As a result of examining the relationship between the two, the concentration and pH were determined by the following inequality 8.7-0.8C ₂ ≧ pH ₂ ≧ 7.1-0.6C ₂ (where C ₂ and pH ₂ are neutralization treatments) The relationship expressed by the concentration of sodium perborate (weight% in terms of anhydrous salt and pH) on the hair at the time, that is, when the concentration and pH are surrounded by the quadrilateral in FIG. 2, the wave down, the wave efficiency and the elasticity It has been found that satisfactory results are obtained for all of the recovery rates.

The concentration (in terms of anhydrous salt) and the pH of the aqueous solution of sodium perborate on the hair during the neutralization treatment are pH> 8.7.
The relationship of -0.8c, that is, in FIG.
Above this, the elastic recovery decreases and the hair tends to be damaged. Further, it is not preferable that the relationship of pH <7.1-0.6c, that is, if the pH is lower than the straight line B in FIG.

In order to achieve the effects of the present invention of reducing the elastic modulus and the wave efficiency due to the repeated permanent treatment, it is necessary that the concentration and the pH of the neutralizing agent on the hair during the permanent treatment are within the above ranges. is there. However, in the permanent treatment, the neutralizing agent treatment is performed after the treatment of the first agent. Usually, the first agent is washed with water, wiped off with a towel, and dried.
Contains significant amounts of moisture. Also, since the neutralizing agent is used in approximately the same amount as the hair, the neutralizing agent is diluted with this moisture. Therefore, the concentration of the stock solution of the neutralizing agent used in the present invention is adjusted to a higher concentration in consideration of the amount used and the degree of dryness of the hair so that the concentration after dilution with the water falls within the above range. Must be used.

When the concentration of the neutralizing agent is previously increased to a high level, the pH of the solution is slightly increased, so that the pH of the stock solution of the neutralizing agent used is adjusted to the optimum condition on the hair during the permanent treatment. It needs to be adjusted to a lower range.

The present inventors have studied the dilution of the neutralizing agent by water contained in the hair and the change in pH.
In both cases, the moisture contained in the hair differs depending on the number of times the permanent wave is repeatedly performed. Therefore, it is found that the dilution effect by the moisture in the hair increases as the number of the permanents increases, and the pH range also changes according to the number of the permanents. Was. As shown in Examples below,
According to the result of the measurement of the water content in the hair, the changes in the concentration and the pH are as shown in Table 1 below.

[0020]

[Table 1]

In consideration of the above-mentioned changes in the concentration and pH, the concentration of the neutralizing agent stock solution is optimally 1.5 to 5.4% by weight, preferably 2.4 to 4.2% by weight (in terms of anhydrous salt). There also concentration and pH of the _{relationship, 8.5-0.5C 1 ≧ pH 1 ≧ 7.0-0.4C} 1 ( sodium perborate concentration of C ₁ and pH ₁ during neutralizer formula ( Weight percent in terms of anhydrous salt) and pH),
That is, when a neutralizing agent having a concentration and a pH surrounded by the quadrangular shape in FIG. 1 is used and applied to the hair, a permanent wave treatment with little reduction in the elastic modulus and the wave efficiency of the hair is performed in the actual operation.

Since the pH of the neutralizing agent may change due to the contact with the hair and the effect of the present invention may be impaired, abrupt pH change is suppressed and neutralization is performed to maintain a desired pH. It is desirable to add a buffer to the agent. Examples of the buffer include succinic acid, potassium dihydrogen phosphate and the like.

The permanent wave method according to the present invention uses the above-mentioned aqueous solution of sodium perborate as a neutralizing agent (second agent). In the method of the present invention, the first agent generally used as the first agent is used. It can be arbitrarily selected from agents. Examples of such a first agent include thioglycolic acid, ammonium thioglycolate, and cysteine.

Further, various additives are added to the neutralizing agent for permanent wave comprising the aqueous solution of sodium perborate of the present invention in order to enhance the action and effect of the permanent wave treatment within a range not to impair the object and effect of the present invention. Can be added. Examples of such additives include hydrolysates of proteins.

In addition, for example, mink oil for improving the feel of hair after permanent waving,
Additives, such as silicon, can also be included.

The treatment conditions for fixing the wavy hair using the permanent wave neutralizing agent of the present invention include a normal neutralizing agent treatment temperature, for example, 20 ° C. to 4 ° C.
The treatment is preferably performed at 0 ° C., preferably at 25 to 35 ° C. for 15 to 20 minutes.

[0027]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, the definition and measurement method of the physical properties of the hair subjected to the permanent treatment in Examples and Comparative Examples are as follows.

(1) Elastic recovery rate (G _n / G ₀ ) The hair before adding the first agent was left in water for 15 minutes to give a constant strain of 1.5% to the hair, and the stress generated at that time was measured. , The initial elastic modulus G ₀ before the permanent treatment is calculated.
1.5% on the hair after repeating the permanent treatment n times
From the stress generated, the elastic modulus after the permanent treatment was defined as G _n , and the ratio G _n / G ₀ (%) was defined as the elastic recovery rate.

(2) Wave Efficiency (WI _n ) The hair having a length of 12 cm was pulled 1.5% before the first agent was added.
The length of the stretched hair is set to ΔL ₀ , and the difference between the length of the stretched hair after the n-times permanent treatment and the length before the stretching (12 cm) is set to ΔL _n, and ΔL _n / Δ
The L ₀ was the wave index.

(3) 20% Index The hair after the permanent treatment is made at a constant speed (5 mm / min).
When the strain reaches 20%, the strain is relaxed at the same speed as the tension. The area ratio based on the value of the following equation in the stress-strain hysteresis curve of FIG. 3 obtained here was defined as a 20% index. I ₂₀ = S _a / S _b where S _a : integrated value of hysteresis curve during tension S _b : integrated value of hysteresis curve during relaxation

[Example 1] (Reduction with the first agent and collection of standard hair sample) Hair of a healthy woman having no history of permanent and hair dyeing was collected, and a hair having a diameter of 60 to 70 µ and having no fineness was obtained from the sample. And reducing it with the first permanent agent by the following method. Attach a glass column whose temperature can be adjusted to a tensile tester, pass through the column, and fix 12 cm of hair between chucks in water, where the initial elastic modulus G before permanent treatment is set.
After measuring ₀ , the water is removed and replaced with a permanent first agent (ammonium thioglycolate concentration 6%, pH 9.0) consisting of a mixture of ammonium thioglycolate, ammonium bicarbonate and ammonia. As the reduction of the hair progresses, the hair is relaxed, so the relaxation rate is measured, and a sample whose relaxation rate is within a certain range after 5 minutes is used as a standard hair sample for the test, and the reduction is totaled. After continuing for 15 minutes, the first agent in the column is removed and washed with distilled water.

(Treatment of Hair Sample with Neutralizing Agent) Sodium perborate tetrahydrate (NaBO ₃ .4H ₂ O) was dissolved in water, potassium dihydrogen phosphate was added, and the pH was 6.7, and the concentration was 1 A 20% by weight (in terms of anhydrous salt, hereinafter the same) aqueous sodium perborate solution was prepared, and this was used as a neutralizing agent (second agent), and the hair reduced by the first agent was temperature-controlled to 30 ° C. After filling the filled column for 15 minutes, the neutralizing agent was removed from the column, washed with water, left in water for 5 minutes, and
Measuring the elastic modulus G ₁ in the hair after round permanent treatment.
Under the same conditions, this permanent treatment was repeated a total of three times, and the elastic modulus G ₀ at a constant strain given in the water before addition of the first agent obtained on the chart and the elastic modulus G obtained after the permanent treatment three times were repeated. _The elastic recovery was measured from the ratio G ₃ / G ₀ to ₃ .

Further, according to the methods (2) and (3),
The wave index (WI ₃ ) and the 20% index after the permanent treatment was repeated three times were measured. Table 2 shows the results.

Example 2, Comparative Examples 1 and 2 In Example 1, the pH of the aqueous sodium perborate solution was changed to 7.
A permanent treatment test was repeated three times in the same manner as in Example 1 except that the test was changed to 5, 6, and 6.3. The results are shown in Table 2. A low pH solution has a high elastic recovery rate but a large wave down.

Examples 3 to 5 Example 1 was repeated except that sodium perborate having a concentration of 1.90% by weight was used and the pH was changed to 6.3, 7.0 and 6.0, respectively.
The permanent treatment test was repeated three times in the same manner as described above. Table 2 shows the results. In the pH range in this range, a well-balanced result was obtained in both the elastic recovery rate and the wave down.

[Examples 6 and 7, Comparative Examples 3 and 4]
, A permanent treatment test was repeated three times in the same manner as in Example 1 except that sodium perborate having a concentration of 2.4% by weight was used and the pH was changed to 6, 6.3, 5.5 and 6.7, respectively. Done. Table 2 shows the results. In the low pH range, the wave-down was large, and in the high pH range, the elastic recovery was poor.

Example 8, Comparative Examples 5 to 6 In Example 1, sodium perborate having a concentration of 3.0% by weight was used.
A permanent treatment test was repeated three times in the same manner as in Example 1 except that the pH was changed to 5.5, 5.2 and 6.3, respectively. Table 2 shows the results.

[Comparative Example 7]
A permanent treatment test was repeated three times in the same manner as in Example 1 except that 6% by weight of sodium perborate was used and the pH was 5.3. Table 2 shows the results.

Comparative Examples 8 to 10 In the same manner as in Example 1, except that sodium perborate having a concentration of 4.2% by weight was used and the pH was changed to 5.3 to 6.0. The permanent treatment test was repeated twice. Table 2 shows the results
Shown in If the concentration of the aqueous sodium perborate solution exceeds 3.3% by weight, good results cannot be obtained regardless of the pH.

[0040]

[Table 2]

From the results obtained in the above Examples and Comparative Examples, the relationship between the pH and the elastic recovery (G _n / G ₀ ), and the pH and the pH at the concentrations of 1.9% by weight and 3.0% by weight, respectively. FIG. 4 shows the relationship of the 20% index. As is apparent from FIG. 4, the aqueous sodium perborate solution preferably has a low concentration and a low pH in order to improve the elastic recovery rate. However, when the concentration and the pH are reduced, the 20% index is reduced. Therefore, the elastic recovery rate and 2
In order to maintain both of the 0% indices at or above a certain level, it is necessary to select the concentration and pH in optimal ranges.

Therefore, the results of the examples and comparative examples are arranged as shown in FIG. 5 based on the relationship between the elastic recovery rate (G _n / G ₀ ) and the 20% index. In FIG. 5, the concentration, p
Example of the present invention where H is in a specific range (black mark)
Indicates that both the elastic recovery rate (G _n / G ₀ ) and the 20% index are excellent, while the comparative example (white background mark) shows that the elastic recovery rate and the 20% index are both excellent. Or both have poor properties. In the comparative examples having a low 20% index, the concentration and pH are all in the lower left part of the concentration and pH range in the present invention shown in FIG. In the comparative example having a low elastic recovery rate, the concentration and the pH were in the upper right part of the above range, or the concentration of the aqueous solution itself was 3.3.
Because it is higher.

[Comparative Examples 11 to 15] Instead of sodium perborate as a neutralizing agent, an aqueous sodium bromate solution conventionally used as a neutralizing agent was used, the pH was maintained at 6, and the sodium bromate concentration was 1. 0 to 10.0 is changed to% by weight, subjected to permanent treatment test repeated three times in the same manner as in example 1 was examined the relationship between the concentration and the elastic recovery (G _n / G ₀₎ and 20% index. Table 3 shows the results. FIG. 6 shows the results together with the numerical values of the embodiment of the present invention.

[0044]

[Table 3]

The aqueous sodium bromate solution having a pH of 7 is in a typical pH range of a commercially available aqueous sodium bromate solution used as a neutralizing agent.
As a result, it can be seen that the present invention is located in the upper right region as compared with the aqueous sodium bromate solution when compared with the examples of the present invention. More specifically, when an aqueous solution of sodium bromate is used as a neutralizing agent, if the 20% index is to be maintained at a certain level or more, for example, 64% or more, the concentration of the aqueous sodium bromate solution is 8.0% by weight or more. When such a high-concentration solution is used, the elastic recovery after the permanent treatment is repeated about three times is about 36%, and the hair damage due to the permanent treatment is large, and the wave index is low. While the wave efficiency is poor, a sufficiently high elastic recovery rate is obtained even with a 20% index of 64% or more in the results of the examples of the present invention.
It can be seen that the present invention is superior to the aqueous sodium bromate solution because the wave down is equal to or smaller than that and the elastic recovery rate and the wave efficiency can be maintained high.

[Experimental Example 1] (Measurement of moisture in hair subjected to permanent waving treatment) Hair whose weight was precisely weighed was wound around a rod, ammonium thioglycolate was used as the first permanent agent, and a concentration of 8% was used as the neutralizing agent. The same treatment as that of an actual permanent wave was performed by using an aqueous sodium perborate solution having a pH of 5.5 and using the same amount of the first agent and the neutralizing agent as that of the hair. The hair after the wave treatment and the neutralization treatment was washed with water each time, the surface was dried by blotting with a filter paper, and the weight of the dried hair was measured. This treatment was repeated five times, and the moisture in the hair after the first agent treatment and drying, that is, the hair immediately before receiving the neutralizing agent treatment, when the permanent wave treatment was repeatedly performed was measured. The results are shown in Table 4 below.

[0047]

[Table 4]

Since the amount of the neutralizing agent used is usually approximately equal to the weight of the hair, the results of the above-mentioned water measurement show that when the hair after treatment with the first agent and the dried neutralizing agent is treated with the neutralizing agent, Since the concentration of the aqueous sodium borate solution is diluted in the range of 1.47 times to 1.63 times, the concentration of the aqueous solution of sodium perborate on the hair during the neutralization treatment is reduced to 1.0 to 3.3% by weight. It has been found that an aqueous solution of sodium perborate having a concentration of 1.5 to 5.4 may be used for this purpose.

In this way, the pH of the virgin hair is 0.09 at the upper limit concentration and 0.09 at the lower limit concentration by making the aqueous solution of sodium perborate of the stock solution of the neutralizing agent actually used 1.47 times to 1.63 times. After the permanent wave treatment, the concentration increased by 0.17 at the upper limit concentration and 0.10 at the lower limit concentration.

From these results, the concentration and pH of the aqueous solution of sodium perborate in the neutralizer stock solution actually used were
It is derived that those in the range of the quadrilateral of FIG. 1 are optimal.

[0051]

The aqueous solution of sodium perborate of the present invention having a specific range of pH and concentration is used as a neutralizing agent for permanent treatment. By the preparation, the wave down is small, and the decrease in the elastic modulus and the decrease in the wave efficiency due to the repeated permanent treatment are smaller than the conventionally used neutralizing agents such as sodium bromate. Can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing the concentration and pH range of a neutralizing agent for permanent waves of the present invention.

FIG. 2 shows the results of neutralization treatment using the neutralizing agent of the present invention.
The figure which shows the sodium perborate aqueous solution density | concentration on hair, and pH range.

FIG. 3 is a stress-strain hysteresis curve for calculating a 20% index.

FIG. 4 shows the relationship between pH, hair elastic modulus recovery rate (G ₃ / G ₀ ), and a 20% index when a permanent treatment was repeated three times using an aqueous solution of sodium perborate as a neutralizing agent. Graph.

FIG. 5 is a graph showing the relationship between the elastic modulus recovery rate (G ₃ / G ₀ ) of hair subjected to permanent treatment three times repeatedly using a sodium perborate aqueous solution as a neutralizing agent and a 20% index.

FIG. 6 is a graph showing the relationship between the elastic recovery rate (G _n / G ₀ ) of hair subjected to permanent treatment three times repeatedly using the aqueous sodium bromate solution of the present invention and the conventional method, and a 20% index.

[Explanation of symbols]

 A: The upper limit of the pH of the aqueous sodium perborate solution of the present invention B: The lower limit of the pH of the aqueous sodium perborate solution of the present invention: Hysteresis curve at the time of tension: Hysteresis curve at the time of relaxation

Claims (4)

[Claims] 1. A permanent wave of hair comprising an aqueous solution of sodium perborate having a concentration (in terms of anhydrous salt) of 1.5 to 5.4% by weight and a relationship between the concentration and pH satisfying the following inequality: For neutralizing agent. 8.5-0.5 C ₁ ≧ pH ₁ ≧ 7.0-0.4 C ₁ (where C ₁ and pH ₁ are the concentration of sodium perborate (weight% in terms of anhydrous salt) and pH in the neutralizing agent) 2. The permanent wave neutralizing agent comprising an aqueous solution of sodium perborate according to claim 1, wherein the concentration thereof (in terms of an anhydrous salt) is 2.4 to 4.2% by weight. 3. A method for neutralizing a permanent wave, comprising treating hair with the neutralizing agent according to claim 1 or 2. 4. A neutralizing agent comprising the aqueous solution of sodium perborate according to claim 1 or 2, wherein the concentration of the aqueous solution of sodium perborate on the hair during the neutralization treatment (in terms of anhydrous salt) is 1.0 to 3; A permanent wave neutralization method, wherein the treatment is carried out under a condition of 0.3% by weight and a relation between concentration and pH satisfying the following inequality: 8.7-0.8 C ₂ ≧ pH ₂ ≧ 7.1-0.6 C ₂ (where C ₂ and pH ₂ are the concentration of sodium perborate on the hair during the neutralization treatment (weight% in terms of anhydrous salt) and pH)