Methods for straightening hair, and hair treatment products.

Abstract

This invention provides a method for making hair easier to straighten and a hair treatment agent. [Solution] The method for straightening hair includes the following steps (a) to (d): (a) The process of treating hair using a hair straightener. (b) A step following step (a), in which a hair treatment agent containing an organic acid and having a pH of less than 3.0 is applied to the hair. (c) After step (b), a step to dry the hair. (d) After step (c), a step in which the hair is treated with a hair straightener. The hair treatment agent is the hair treatment agent used in step (b) above.

Description

Technical Field

[0001] The present invention relates to a method for straightening hair and a hair treatment agent.

Background Art

[0002] In recent years, as a hair treatment method for improving the texture and appearance of hair, a method has been reported in which after treating hair with an acid, the acid is washed and removed, and then heat treatment is performed using a hair straightening iron. By this method, the hair shape can be adjusted and straightened.

[0003] As an example of the above method, in Patent Document 1, a semi-permanent hair correction method includes the following steps: a) applying a solution containing glyoxylic acid to the hair; b) continuously contacting the hair with the substance for 15 to 120 minutes; c) drying the hair; d) correcting the hair using a hair correction iron at a temperature of 200 ± 50°C. A method characterized by having these steps is disclosed.

[0004] Also, in Patent Document 2, an acid treatment of applying an acidic first composition for hair containing an acid and / or its salt to the hair, a washing treatment of washing the hair, a silicone treatment of applying a liquid second composition for hair containing silicone to the hair, a drying treatment of drying the hair, and a heat treatment of bringing a heating element with a set temperature of 100°C or higher into contact with the hair are provided. A hair treatment method characterized by this is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Methods using acid and heat, such as those described in Patent Documents 1 and 2, have also been proposed for straightening hair. However, even with methods using acid and heat, hair with strong waves or curls may not be sufficiently straightened. Therefore, there is a need for new proposals for methods that make it easier to straighten hair.

[0007] In view of the above circumstances, an object of the present invention is to provide a new method for making hair easier to straighten. Another object of the present invention is to provide a hair treatment agent that can make hair easier to straighten. [Means for solving the problem]

[0008] The inventors diligently conducted research to further improve a method for straightening hair using acid and heat. As a result, the inventors discovered that if the hair is straightened using a hair straightening iron before applying a hair treatment agent containing organic acid, it becomes easier to straighten the hair. The inventors then conducted further research and completed the inventions described below.

[0009] [1] is a method for straightening hair, which includes the following steps (a) to (d). (a) The process of treating hair using a hair straightener. (b) A step following step (a), in which a hair treatment agent containing an organic acid and having a pH of less than 3.0 is applied to the hair. (c) After step (b), a step to dry the hair. (d) After step (c), a step in which the hair is treated with a hair straightener.

[0010] Method [2] is the same as method [1], wherein in step (a), the set temperature of the hair straightener is 140°C or higher.

[0011] Method [3] is method [1] or [2], wherein in step (b), the organic acid incorporated into the hair treatment agent is one or more selected from the group consisting of glyoxylic acid, levulinic acid, glycolic acid, lactic acid, salicylic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, malic acid, and citric acid.

[0012] Method [4] is one of the methods [1] to [3], wherein in step (b), the amount of organic acid added to the hair treatment agent is 5% by mass or more.

[0013] Method [5] is one of the methods [1] to [4], wherein in step (b), the pH of the hair treatment agent is 2.5 or less.

[0014] Method [6] is one of the methods [1] to [5], wherein step (b) involves heating the hair to which the hair treatment agent has been applied.

[0015] Method [7] is one of the methods [1] to [6], wherein in step (d), the set temperature of the hair straightener is 160°C or higher.

[0016] The hair treatment agent [8] is used in step (b) of any of the methods [1] to [7], contains an organic acid, and has a pH of less than 3.0. [Effects of the Invention]

[0017] According to the method of the present invention, it becomes possible to make hair easier to straighten. Furthermore, the hair treatment agent according to the present invention makes it easier to straighten hair. [Brief explanation of the drawing]

[0018] [Figure 1]Photographs of hair bundles before straightening the hair ((A): hair bundle 1, (B): hair bundle 2, (C): hair bundle 3). [Figure 2] Photographs of hair bundles before and after the hair treatment of Example 1 (left: state before the hair treatment of Example 1, right: state after the hair treatment of Example 1). [Figure 3] A sheet showing hair types (schematic diagrams showing the state of one hair in each of 12 types of 1a to 4c and a model image showing the entire head hair).

Mode for Carrying Out the Invention

[0019] <Method for Straightening Hair According to the First Embodiment> Hereinafter, a method for straightening hair according to the first embodiment of the present invention (hereinafter referred to as "the method of the first embodiment") will be described by way of example.

[0020] The method of the first embodiment is a method for straightening hair, including the following steps (a) to (d). (a) Step of treating the hair using a hair straightening iron (b) Step of applying a hair treatment agent containing an organic acid and having a pH of less than 3.0 to the hair after step (a) (c) Step of drying the hair after step (b) (d) Step of treating the hair using a hair straightening iron after step (c)

[0021] The method of the first embodiment may further include a step of washing and drying the hair using a hair washing composition before step (a). Examples of the hair washing composition include known hair shampoos containing an anionic surfactant.

[0022] (Step (a)) In the method of the first embodiment, step (a) is a step of treating the hair using a hair straightening iron. Step (a) is preferably performed on dried hair. In step (a), the hair may be straightened by applying tension to the hair while heating it with a hair straightening iron. In the following description, the hair treatment in step (a) may be referred to as "pre-ironing treatment".

[0023] The hair straightener used in step (a) is preferably equipped with a pair of opposing metal plate-like bodies as heating elements. In this case, the hair treatment using the hair straightener may involve placing the hair between the opposing heating elements, and then moving the hair straightener while maintaining the state of the hair being held, allowing the held hair to slide. When sliding the held hair against the straightener, it is preferable that tension is applied to the hair. From the viewpoint of making it easier to straighten the hair, the set temperature of the heating elements of the hair straightener is preferably 140°C or higher, more preferably 160°C or higher, and even more preferably 180°C or higher. On the other hand, from the viewpoint of minimizing damage to the hair, the set temperature of the heating elements is preferably 230°C or lower, and more preferably 210°C or lower. When using the hair straightener on hair that has been washed with a hair washing composition and dried, it is preferable that the temperature of the heating elements of the hair straightener be 30°C or higher than the hair temperature when dry.

[0024] In step (a), a commercially available hair straightener can be used. Examples of commercially available products include BaBylissPRO's "NANO TITANIUM," Hakko's "ADST Premium DS," and Koizumi Seiki's "VSI-1009 / PJ." From the standpoint of making it easier to straighten the hair, it is preferable to use a hair straightener that can set the heating element to a higher temperature.

[0025] The number of times the hair straightening iron is used in step (a) should be set appropriately according to the condition of the hair. For example, the number of times is one or more, but since it becomes easier to straighten the hair with more times, two or more times is preferable, and three or more times is even more preferable. On the other hand, for example, the number of times is 10 or less, but from the viewpoint of minimizing damage to the hair, five or less times is preferable.

[0026] The processing time for the hair straightening iron in step (a) is not particularly limited, but the contact time with the hair in one processing pass may be 0.5 seconds or more and 2 seconds or less per 10 cm of hair length, and preferably about 1 second.

[0027] (Step (b)) In the method of the first embodiment, step (b) is a step in which a hair treatment agent containing an organic acid and having a pH of less than 3.0 (hereinafter referred to as "hair treatment agent used in the method of the first embodiment") is applied to the hair after step (a). The hair treatment agent used in the method of the first embodiment may be applied to the hair by means such as coating it with water. Step (b) may be started, for example, immediately after step (a) is completed, within 20 minutes, or within 10 minutes. Furthermore, it is preferable that step (b) be started, for example, without wetting the hair after step (a) is completed.

[0028] (Hair treatment agent) The hair treatment agent used in the method of the first embodiment contains one or more organic acids and has a pH of less than 3.0.

[0029] As the organic acid, for example, an organic acid having 2 to 10 carbon atoms may be used. Furthermore, from the viewpoint of excellent penetration into hair, an organic acid with a molecular weight of 400 or less is preferred. Alternatively, an organic acid with a molecular weight of 50 to 400 may be used.

[0030] As the organic acid, one or more organic acids selected from monocarboxylic acids, dicarboxylic acids, and tricarboxylic acids may be used. Examples of monocarboxylic acids include glyoxylic acid, levulinic acid, glycolic acid, lactic acid, and salicylic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, succinic acid, tartaric acid, and malic acid. Examples of tricarboxylic acids include citric acid. As for the organic acid, glyoxylic acid is preferred from the viewpoint of making it easier to straighten hair and increasing the duration of the straightening effect.

[0031] In the hair treatment agent used in the method of the first embodiment, the amount of organic acid can be set as appropriate. For example, the amount of organic acid is 3% by mass or more, but from the viewpoint of making it easier to straighten the hair and increasing the duration of the straightening effect, 5% by mass or more is preferable, 7.5% by mass or more is more preferable, and 10% by mass or more is even more preferable. In addition, the amount of organic acid is 40% by mass or less, and from the viewpoint of suppressing damage to the hair, 30% by mass or less is preferable.

[0032] The hair treatment agent used in the method of the first embodiment may contain, in addition to organic acids, components used in known hair compositions applied to hair as optional components. Examples of these optional components include water, cationic surfactants, nonionic surfactants, higher alcohols, lower alcohols, polyhydric alcohols, silicones, chelating agents, fragrances, and preservatives.

[0033] The hair treatment agent used in the method of the first embodiment may, for example, contain water. The amount of water used in the hair treatment agent in the method of the first embodiment is not particularly limited, but for example, it is 10% by mass or more and 97% by mass or less.

[0034] The hair treatment agent used in the method of the first embodiment is preferably in a cream form, for example, from the viewpoint of being easy to apply to hair due to its appropriate viscosity. The hair treatment agent used in the method of the first embodiment may be, for example, a cream containing a higher alcohol and a cationic surfactant.

[0035] The higher alcohol can be a monohydric alcohol with 12 to 22 carbon atoms. Examples of higher alcohols include linear higher alcohols (e.g., myristyl alcohol, cetanol, oleyl alcohol, stearyl alcohol, behenyl alcohol, etc.) and branched higher alcohols (e.g., hexyldecanol, isocetyl alcohol, isostearyl alcohol, octyldodecanol, decyltetradecanol, etc.). The amount of higher alcohol used in the hair treatment agent according to the method of the first embodiment is, for example, 0.5% by mass or more and 15% by mass or less.

[0036] Examples of cationic surfactants include mono-long-chain alkyltrimethylammonium salts, di-long-chain alkyldimethylammonium salts, tri-long-chain alkylmonomethylammonium salts, benzalkonium-type quaternary ammonium salts, mono-alkyl ether-type quaternary ammonium salts, mono-alkylamide-type quaternary ammonium salts, fatty acid ester amine salts, fatty acid amide amine salts, and urea condensed amine salt-type tertiary amine salts (Arcover-type tertiary amine salts). The above "long-chain alkyl" may be an alkyl group having 12 to 28 carbon atoms. The amount of cationic surfactant used in the hair treatment agent in the method of the first embodiment is, for example, 0.1% by mass or more and 10% by mass or less.

[0037] (pH) The pH of the hair treatment agent used in the method of the first embodiment is less than 3.0, but from the viewpoint of making the hair closer to a straighter state, a pH of 2.5 or less is more preferable, and 2.0 or less is even more preferable. On the other hand, from the viewpoint of reducing hair damage caused by swelling of the hair due to acid, the pH of the hair treatment agent used in the method of the first embodiment is preferably 0.5 or higher, more preferably 0.75 or higher, and even more preferably 1.0 or higher. The above pH values ​​are those obtained by measuring the hair treatment agent at 25°C using a known pH meter.

[0038] The pH of the hair treatment agent used in the method of the first embodiment may be adjusted by adding another acid or alkali in addition to the organic acid that is included. For example, an inorganic acid (such as phosphoric acid) may be used as the acid. For the alkali, an organic alkali (such as alkanolamine) or an inorganic alkali (such as potassium hydroxide or sodium hydroxide) may be used.

[0039] In step (b), when applying the hair treatment agent used in the method of the first embodiment to the hair, the hair is left in contact with the hair treatment agent for a certain period of time. This waiting time can be set as appropriate, but from the viewpoint of making the hair straighter and minimizing damage to the hair, it is preferable to leave it for 15 minutes or more and 90 minutes or less. During the waiting period, the hair to which the hair treatment agent used in the method of the first embodiment has been applied may be heated by a known method. The means for heating the hair can be set as appropriate, for example, a device for heating hair may be used. The device may be equipped with, for example, a chamber, hood, etc. for heating hair. The temperature setting is not particularly limited, but for example, it is preferable to set it to 40°C or more and 60°C or less.

[0040] (Process (c)) In the method of the first embodiment, step (c) is a step of drying the hair after step (b).

[0041] In step (c), when processing the hair with a hair straightener in step (d), which will be described later, it is preferable to wash the hair to which the hair treatment agent used in the first embodiment has been applied before drying the hair, from the viewpoint of making the hair slippery and easy to handle. The washing of the hair is not particularly limited, but for example, it may be rinsed with water, or it may be rinsed with water after using the hair washing composition described above.

[0042] In step (c), the hair may be dried with cool air or air drying, but from the viewpoint of drying the hair in a short time, it is preferable to dry the hair with hot air from a hair dryer. Furthermore, when drying the hair, from the viewpoint of making the hair closer to a straight shape, it is preferable to blow dry the hair using a known hair comb or hair brush. Blow drying is a process in which tension is applied to the hair using a hair comb or the like, and the hair is dried with hot air from a hair dryer while shaping the hair into a straight form.

[0043] (Step (d)) In the method of the first embodiment, step (d) is a step in which the hair is treated with a hair straightener after step (c). In the following description, the hair treatment in step (d) may be referred to as "post-ironing treatment".

[0044] In step (d), the process can be the same as in step (a) when treating the hair using the hair straightener described above, except for the temperature setting and the number of treatment cycles. The hair straightener used in step (d) and the hair straightener used in step (a) may be the same or different.

[0045] In step (d), the set temperature of the heating element of the hair straightening iron is preferably 160°C or higher, more preferably 190°C or higher, and even more preferably 210°C or higher, from the viewpoint of making it easier to straighten the hair. On the other hand, the set temperature of the heating element is preferably 250°C or lower, and more preferably 230°C or lower, from the viewpoint of minimizing damage to the hair.

[0046] The number of times the hair straightening iron is used in step (d) should be set appropriately according to the condition of the hair. For example, the number of times is 3 or more, but since it is possible to straighten the hair more times, 5 or more times is preferable, 8 or more times is more preferable, and 10 or more times is even preferable. On the other hand, from the viewpoint of minimizing damage to the hair, 20 times or less of processing is preferable.

[0047] (Target hair) In the method of the first embodiment, the target hair is not particularly limited and may be hair that has been treated with a straightening iron or hair that has not been treated with a straightening iron. As the target hair, for example, frizzy hair or curly hair may be used, from the viewpoint that the straightening of the hair will be visually clear before and after using the method of the first embodiment. Frizzy hair refers to hair that is not straight but has a strong wave or curl due to congenital or acquired factors, resulting in excessive volume in the overall appearance of the hair. Curly hair refers to hair that is not straight but has a wave or curl.

[0048] (Hair type) The target hair can be classified into four categories according to its condition, as follows: 1: Straight (straight hair) 2: Wavy (wavy hair) 3: Curly (curly hair) 4: Coiled hair

[0049] Furthermore, within a single classification of hair, it can be further divided into three stages (a, b, c) according to the strength of the curl. For example, in the case of 1: straight hair, it can be classified into types 1a, 1b, and 1c in order of increasing curliness. In the case of 2: wavy hair, it can be classified into types 2a, 2b, and 2c in order of increasing waveiness. In the case of 3: curly hair, it can be classified into types 3a, 3b, and 3c in order of increasing curliness. In the case of 4: coily hair, it can be classified into types 4a, 4b, and 4c in order of increasing coil diameter.

[0050] The target hair can be divided into 12 types by combining four classifications (1-4) and three stages (a, b, c). For example, the target hair may be divided into one of the 12 types by referring to the sheet shown in Figure 3. The sheet in Figure 3 shows schematic diagrams of a single hair strand and model images of the entire head of hair for each of the 12 types, 1a-4c. The hair type of the target hair may be determined by either (i), (ii), or both, using the sheet in Figure 3. (i) Observe the condition of the hair to be classified, and select the closest condition from the schematic diagrams showing the condition of one strand of hair for each of the 12 types on the sheet in Figure 3 to determine the hair type of the target hair. (ii) Observe the overall condition of the hair of the person to be classified, and select the closest representation from the 12 model images of the entire hair of each type on the sheet in Figure 3 to determine the person's hair type.

[0051] Furthermore, when classifying target hair types using method (i), the target hair type of the target person may be determined by arbitrarily selecting several strands of hair from the person to be classified and referring to the sheet in Figure 3 to select the closest hair type.

[0052] <Hair treatment agent according to the second embodiment> The following description will use a hair treatment agent according to the second embodiment of the present invention (hereinafter referred to as "the hair treatment agent of the second embodiment") as an example.

[0053] The hair treatment agent of the second embodiment is a hair treatment agent used in step (b) of a method for straightening hair, which includes the following steps (a) to (d), and contains an organic acid and has a pH of less than 3.0. (a) The process of treating hair using a hair straightener. (b) A step after step (a) in which a hair treatment agent is applied to the hair. (c) After step (b), a step to dry the hair. (d) After step (c), a step in which the hair is treated with a hair straightener.

[0054] By using the hair treatment agent of the second embodiment in the method for straightening the hair, it becomes possible to make the hair easier to straighten. The hair treatment agent of the second embodiment is the same as the hair treatment agent used in the method of the first embodiment, so its description is omitted. Also, each step (a) to (d) in the method for straightening the hair is the same as each step (a) to (d) in the method of the first embodiment, so its description is omitted. [Examples]

[0055] The method of the first embodiment and the hair treatment agent of the second embodiment will be described in detail below using examples. The present invention should not be interpreted as being limited based on the description of these examples.

[0056] (Manufacturing of hair treatment agents 1-8) As described below, we manufactured hair treatment agents 1-8 containing organic acids.

[0057] Hair treatment agents 1 to 8 were manufactured by mixing components selected from the listed ingredients using conventional methods to achieve the compositions shown in Tables 1 and 2 below. The numbers in the ingredient columns of Tables 1 and 2 represent mass percent, and "-" indicates that the ingredient was not included. "Appropriate amount" of potassium hydroxide refers to the amount that results in the pH of the hair treatment agent being the value shown in Tables 1 and 2, and "Amount of purified water to reach 100%" refers to the amount of purified water that results in a total blend of purified water and other components being 100% by mass. The pH values ​​were measured using a known meter at 25°C for the hair treatment agents. In hair treatment agents 1 to 3 shown in Table 1, the amounts of glyoxylic acid, levulinic acid, and glycolic acid were adjusted so that the molar concentration of each organic acid was 2M. Hair treatment agents 1 to 3 shown in Table 1 were O / W type creams, while hair treatment agents 4 to 8 shown in Table 2 were liquids.

[0058] (Ingredients used) Stearyltrimethylammonium chloride, isopropanol, cetanol, phenoxyethanol, glyoxylic acid, levulinic acid, glycolic acid, potassium hydroxide, purified water

[0059] [Table 1]

[0060] [Table 2]

[0061] Using the hair treatment agents 1 to 8 prepared as described above, the hair treatments described in Examples 1 to 16 and Comparative Examples 1 to 6 below were performed.

[0062] (Hair treatment in Examples 1-5 and Comparative Examples 1-2) The hair treatments for Examples 1-5 and Comparative Examples 1-2 were performed according to the following procedure.

[0063] Hair bundles used for hair treatment Hair bundle 1: Multiple hair bundles from the same lot were prepared from commercially available hair bundles from HIS & HER HAIR GOODS CO. (product name CUTICLE WC-EWD; wavy hair (hair type 2c), 30 cm, approximately 2 g; hair bundle (A) in Figure 1), and washed with a 13.5% by mass sodium laureth sulfate aqueous solution.

[0064] (Pre-ironing treatment) In the hair treatments of Examples 1-5 and Comparative Example 2, the hair bundles were dried using warm air from a hair dryer while straightening them by hand. Then, a pre-ironing treatment was performed by setting the temperature of the pair of heating elements in a hair straightening iron to 180°C, placing the hair bundles between the heating elements, and sliding the iron through the hair bundles while straightening them three times. In the hair treatment of Comparative Example 1, the hair bundles were dried using a hair blow-drying treatment (using a hair comb to apply tension to the hair and straighten the hair shape while drying it with warm air from a hair dryer; the same applies hereinafter), and no pre-ironing treatment was performed.

[0065] (Treatment using hair treatment agents) Next, as a treatment using a hair treatment agent, hair treatment agent 1 was applied to each hair bundle in Examples 1-5 and Comparative Example 1, and each bundle was left at room temperature. The hair bundle in Comparative Example 2 was treated with purified water and left at room temperature. The waiting time was 30 minutes for the hair treatments in Examples 1, 3-5, and Comparative Examples 1-2, and 15 minutes for the hair treatment in Example 2. After the waiting time was over, each hair bundle was lightly rinsed with water, and then dried using a hair blow-dry (using a hair comb to apply tension to the hair, straightening the hair shape, and drying it with warm air from a hairdryer).

[0066] (Post-iron treatment) For each dried hair bundle, a hair straightener, the same one used in the pre-ironing treatment, was used to heat-treat it. The pair of heating elements were set to a predetermined temperature, and the hair bundle was placed between the heating elements. The hair bundle was then slid through the straightener while stretching it a predetermined number of times. In Examples 1-2, 5, and Comparative Examples 1-2, the heating element temperature was set to 200°C, in Example 3 to 170°C, and in Example 4 to 230°C. The number of times the hair bundle was slid through the straightener while stretching it was 10 times in Examples 1-4 and Comparative Examples 1-2, and 20 times in Example 5.

[0067] (evaluation) The hair bundles treated in Examples 1-5 and Comparative Example 1 were evaluated for "cohesion upon finishing," "smoothness," and "durability of cohesion."

[0068] (The finished product will be cohesive.) The hair bundles treated in Examples 1-5 and Comparative Examples 1-2 were each fixed to a board so that they were suspended vertically with the ends facing downwards. Then, a hair comb was passed through the suspended hair bundles once, and the width of the hair bundle (cm) was measured by placing a ruler horizontally at the widest part of the bundle. Note that the smaller the hair bundle width (cm), the closer the treated hair is to a straight shape, indicating better manageability in the finished style.

[0069] (Smoothness) Next, using each hair bundle whose width measurement was completed, a sensory evaluation was conducted using the smoothness when fingers were passed through each bundle as an indicator. The sensory evaluation was conducted by three individuals who regularly evaluate hair. The evaluation method involved assigning a score of 1 if the hair bundle was not as smooth as the standard hair bundle, 2 if the smoothness was about the same, 3 if it was slightly smooth, and 4 if it was very smooth. The standard hair bundle was scored at 2 points. The average of the scores from the three individuals was then calculated. In Table 3, the standard hair bundle was the hair bundle that underwent the hair treatment described in Comparative Example 1.

[0070] (Persistence of cohesion) The persistence of manageability was evaluated by washing the treated hair bundles from each example and comparative example with a 13.5% sodium laureth sulfate aqueous solution, rinsing with water, and drying with a hairdryer, repeating this process three times. The hair bundle width (cm) was then measured using the same method as described above for "manageability at the finished state." A smaller hair bundle width (cm) indicates that the treated hair is closer to a straight shape, and therefore exhibits superior manageability.

[0071] Table 3 below shows the hair treatment procedures and evaluation results for Examples 1-5 and Comparative Examples 1-2. Figure 2 shows photographs of the hair bundles before and after the hair treatment in Example 1 (in Figure 2, the example on the left shows the state before the hair treatment in Example 1, and the example on the right shows the state after the hair treatment in Example 1).

[0072] [Table 3]

[0073] As shown in Table 3, the hair bundles treated in Examples 1-5, which included pre-ironing, showed improved "manageability in the finished product" compared to the hair bundles treated in Comparative Example 1, which underwent blow-drying but did not include pre-ironing. Furthermore, the hair bundles treated in Examples 1, 2, 4, and 5 also showed improved "durability of manageability." In addition, the hair bundles treated in Examples 1, 4, and 5 showed superior "smoothness." These results indicate that pre-ironing makes it easier to straighten hair. Moreover, by adjusting the processing time with the hair treatment agent and the conditions of the post-ironing treatment, it is possible to improve the effects of "durability of manageability" and "smoothness."

[0074] (Hair treatment in Example 6 and Comparative Example 3) The hair treatments for Example 6 and Comparative Example 3 were performed according to the following procedure. Hair treatment in Example 6: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 2, and otherwise the same treatment as in Example 1 was performed. Hair treatment in Comparative Example 3: In the hair treatment of Comparative Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 2, and otherwise the same treatment as in Comparative Example 1 was performed.

[0075] (evaluation) The hair bundles treated in Example 6 and Comparative Example 3 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 4, the hair bundle used as the standard was the hair bundle treated in Comparative Example 2.

[0076] Table 4 below shows the hair treatment procedures and evaluation results for Example 6 and Comparative Example 3. For reference, the hair treatment procedures and evaluation results for Comparative Example 2 are also shown.

[0077] [Table 4]

[0078] As shown in Table 4, the hair bundles treated in Example 6, which included pre-ironing, showed improved "manageability at the end of the styling" and "durability of manageability" compared to the hair bundles treated in Comparative Example 3, which underwent blow-drying but did not include pre-ironing. From these results, it can be seen that even when using hair treatment agent 2, pre-ironing makes it easier to straighten hair.

[0079] (Hair treatment in Example 7 and Comparative Example 4) The hair treatments for Example 6 and Comparative Example 3 were performed according to the following procedure. Hair treatment in Example 7: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 3, and otherwise the same treatment as in Example 1 was performed. Hair treatment in Comparative Example 4: In the hair treatment of Comparative Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 3, and otherwise the same treatment as in Comparative Example 1 was performed.

[0080] (evaluation) The hair bundles treated in Example 7 and Comparative Example 4 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 5, the hair bundle used as the standard was the hair bundle treated in Comparative Example 2.

[0081] Table 5 below shows the hair treatment procedures and evaluation results for Example 7 and Comparative Example 4. For reference, the hair treatment procedures and hair bundle evaluation results for Comparative Example 2 are also shown.

[0082] [Table 5]

[0083] As shown in Table 5, the hair bundles treated in Example 7, which included pre-ironing, showed improved "manageability in the finished style" compared to the hair bundles treated in Comparative Example 4, which underwent blow-drying but did not include pre-ironing. This result indicates that pre-ironing makes it easier to straighten hair.

[0084] Of the results shown in Tables 3 to 5, Examples 1 and 6-7 are examples where the only difference in the hair treatment conditions was the hair treatment agent used. Comparing the results of the hair treatments in Examples 1 and 6-7, it was confirmed that the hair treatment in Example 1 (hair treatment using a hair treatment agent containing glyoxylic acid) showed greater improvement in both "manageability at the time of finish" and "durability of manageability" compared to the hair treatments in Examples 6-7 (hair treatment using a hair treatment agent containing levulinic acid or glycolic acid instead of glyoxylic acid). From these results, it can be seen that even when using hair treatment agent 3, using a hair treatment agent containing glyoxylic acid makes it easier to straighten the hair.

[0085] (Hair treatment in Examples 8-1, 9-12, and Comparative Example 5-1) The hair treatments for Examples 8-1, 9-12, and Comparative Example 5-1 were performed according to the following procedure. Hair treatment in Example 8-1: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, and otherwise the same treatment as in Example 1 was performed. Hair treatment in Examples 9-11: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, and the setting temperature of the hair straightener in the pre-ironing treatment was changed to 140°C (Example 9), 160°C (Example 10), and 200°C (Example 11), and otherwise the same treatment as in Example 1 was performed. Hair treatment in Example 12: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, the number of treatments in the pre-ironing treatment was changed to 5, and all other treatments were the same as in Example 1. Hair treatment in Comparative Example 5-1: In the hair treatment of Comparative Example 1 described above, hair treatment agent 1 was changed to hair treatment agent 4 in the treatment using the hair treatment agent, and otherwise the same treatment as in Comparative Example 1 was performed.

[0086] (evaluation) The hair bundles treated in Examples 8-1, 9-12, and Comparative Example 5-1 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 6, the hair bundle used as the standard was the hair bundle treated in Comparative Example 5-1.

[0087] Table 6 below shows the hair treatment procedures and evaluation results for Examples 8-1, 9-12, and Comparative Example 5-1.

[0088] [Table 6]

[0089] As shown in Table 6, the hair bundles treated in Examples 8-1 and 9-12, which included pre-ironing, showed improved "manageability at the end of the styling process" compared to the hair bundles treated in Comparative Example 5-1, which underwent blow-drying and did not include pre-ironing. Furthermore, the hair bundles treated in Examples 8-1 and 10-12 showed improved "smoothness" and "durability of manageability" compared to the hair bundles treated in Comparative Example 5-1. These results indicate that, even when using hair treatment agent 4, pre-ironing makes it easier to straighten hair. It also shows that by setting the conditions for pre-ironing, the effects on "manageability at the end of the styling process," "smoothness," and "durability of manageability" can be further improved.

[0090] (Hair treatment in Examples 13, 8-2, and 5-2) The hair treatments for Example 13, Example 8-2, and Comparative Example 5-2 were performed according to the following procedure. Hair treatment in Example 13: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, a hair blow treatment was performed when drying the hair bundles before the pre-ironing treatment, and the number of treatments in the subsequent pre-ironing treatment was changed to one, and otherwise the same treatment as in Example 1 was performed. Hair treatment in Example 8-2: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, and a hair blow treatment was performed when drying the hair bundles before the pre-ironing treatment. Otherwise, the treatment was the same as the hair treatment of Example 1. Hair treatment in Comparative Example 5-2: In the hair treatment of Comparative Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4, and otherwise the same treatment as in Comparative Example 1 was performed.

[0091] (evaluation) The hair bundles treated in Examples 13, 8-2, and 5-2 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 7, the hair bundle used as the standard was the hair bundle treated in Comparative Example 5-2.

[0092] Table 7 below shows the hair treatment procedures and evaluation results for Example 13, Example 8-2, and Comparative Example 5-2.

[0093] [Table 7]

[0094] As shown in Table 7, the hair bundles treated in Examples 13 and 8-2, which included pre-ironing, showed improved "cohesion," "smoothness," and "durability of cohesion" compared to the hair bundles treated in Comparative Example 5-2, which did not include pre-ironing. These results indicate that even when blow-drying is performed before pre-ironing, pre-ironing makes it easier to straighten hair.

[0095] (Hair treatment in Examples 14-16 and Comparative Example 6) The hair treatments for Examples 14-16 and Comparative Example 6 were performed according to the following procedure. Hair treatment in Examples 14-16 and Comparative Example 6: In the hair treatment of Example 1 described above, hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 5 (Example 14), hair treatment agent 6 (Example 15), hair treatment agent 7 (Example 16), and hair treatment agent 8 (Comparative Example 6), respectively, and otherwise the same treatment as in Example 1 was performed.

[0096] (evaluation) The hair bundles treated in Examples 14-16 and Comparative Example 6 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 8, the hair bundle used as the standard was the hair bundle treated in Comparative Example 5-1.

[0097] Table 8 below shows the hair treatment procedures and evaluation results for Examples 14-16 and Comparative Example 6. For reference, the hair treatment procedures and hair bundle evaluation results for Example 8-1 and Comparative Example 5-1 are also shown.

[0098] [Table 8]

[0099] As shown in Table 8, the hair bundles treated in Examples 8-1 and 14-16 using a hair treatment agent containing glyoxylic acid and a pH of less than 3.0 showed improved "manageability" and "smoothness" compared to the hair bundles treated in Comparative Example 6 using a hair treatment agent containing glyoxylic acid and a pH greater than 3.0. Furthermore, the hair bundles treated in Examples 8-1 and 15-16 using hair treatment agents 4, 6-7 containing 15% or more by mass of glyoxylic acid showed improved "durability of manageability" compared to the hair bundles treated in Example 14 using hair treatment agent 5 containing less than 15% by mass of glyoxylic acid. These results indicate that, in a method of straightening hair, by changing the composition of the hair treatment agent containing organic acids while performing a pre-ironing treatment, the effects of "manageability" and "durability of manageability" can be further improved.

[0100] (Hair treatment in Example 8-3 and Comparative Example 5-3) The hair treatments for Example 8-3 and Comparative Example 5-3 were performed according to the following procedure. Hair treatment in Example 8-3: In the hair treatment of Example 1 described above, hair bundle 1 used for hair treatment was changed to hair bundle 2 described later, and hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4. Otherwise, the same treatment as in Example 1 was performed. Hair treatment in Comparative Example 5-3: In the hair treatment of Comparative Example 1 described above, hair bundle 1 used for hair treatment was changed to hair bundle 2 described later, and hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4. Otherwise, the same treatment as in Comparative Example 1 was performed.

[0101] Hair bundle 2: A commercially available hair bundle from Beaulux (product name: Indian Human Hair Black Hair BS-B4-3; wavy hair (mixture of hair types 2a and 2b), 30cm, approximately 3g; hair bundle (B) in Figure 1)

[0102] (evaluation) The hair bundles treated in Example 8-3 and Comparative Example 5-3 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 9, the hair bundle used as the standard was the hair bundle treated in Comparative Example 5-3.

[0103] Table 9 below shows the hair treatment procedures and evaluation results for Example 8-3 and Comparative Example 5-3.

[0104] [Table 9]

[0105] As shown in Table 9, the hair bundles treated in Example 8-3, which included pre-ironing, showed improved "manageability at the end of the hair styling process," "smoothness," and "durability of manageability" compared to the hair bundles treated in Comparative Example 5-3, which underwent blow-drying but did not include pre-ironing. This improvement in "manageability at the end of the hair styling process" was consistent with the results shown previously (Table 3, etc.). From these results, it can be seen that even when the condition of the treated hair bundles differs, pre-ironing makes it easier to straighten hair in a hair straightening method.

[0106] (Hair treatment in Examples 8-4 and Comparative Examples 5-4) The hair treatments for Example 8-4 and Comparative Example 5-4 were performed according to the following procedure. Hair treatment in Example 8-4: In the hair treatment of Example 1 described above, hair bundle 1 used for hair treatment was changed to hair bundle 3 described later, and hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4. Otherwise, the same treatment as in Example 1 was performed. Hair treatment in Comparative Example 5-4: In the hair treatment of Comparative Example 1 described above, hair bundle 1 used for hair treatment was changed to hair bundle 3 described later, and hair treatment agent 1 used in the treatment using the hair treatment agent was changed to hair treatment agent 4. Otherwise, the same treatment as in Comparative Example 1 was performed.

[0107] Hair bundle 3: Commercially available hair bundle (curly hair (hair type 3c), 30cm, approximately 1g; hair bundle (C) in Figure 1)

[0108] (evaluation) The hair bundles treated in Example 8-4 and Comparative Example 5-4 were evaluated for "cohesion at the finished state," "smoothness," and "durability of cohesion" in the same manner as the hair treatments in Examples 1-5 and Comparative Example 1. In the evaluation of "smoothness" shown in Table 10, the hair bundle used as the standard was the hair bundle treated in Comparative Example 5-4.

[0109] Table 10 below shows the hair treatment procedures and evaluation results for Example 8-4 and Comparative Example 5-4.

[0110] [Table 10]

[0111] As shown in Table 10, the hair bundles treated in Example 8-4, which included pre-ironing, showed improved "manageability at the end of the styling" and "durability of manageability" compared to the hair bundles treated in Comparative Example 5-4, which underwent blow-drying but did not include pre-ironing. This result, in which "manageability at the end of the styling" improved, was consistent with the results shown previously (Tables 3 and 9, etc.). From these results, it can be seen that even when the condition of the treated hair bundles differs, pre-ironing makes it easier to straighten hair in a method of straightening hair.

Claims

1. A method for straightening hair, comprising the following steps (a) to (d). (a) The process of treating hair using a hair straightener. (b) A step after step (a) in which a hair treatment agent containing an organic acid and having a pH of less than 3.0 is applied to the hair. (c) A step to dry the hair after step (b) (d) A step after step (c) in which the hair is treated with a hair straightener.

2. The method according to claim 1, wherein in step (a), the set temperature of the hair straightener is 140°C or higher.

3. The method according to claim 1 or 2, wherein in step (b), the organic acid incorporated into the hair treatment agent is one or more selected from the group consisting of glyoxylic acid, levulinic acid, glycolic acid, lactic acid, salicylic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, malic acid, and citric acid.

4. The method according to claim 1 or 2, wherein in step (b), the amount of organic acid incorporated into the hair treatment agent is 5% by mass or more.

5. The method according to claim 1 or 2, wherein in step (b), the pH of the hair treatment agent is 2.5 or less.

6. The method according to claim 1 or 2, wherein step (b) involves heating the hair to which the hair treatment agent has been applied.

7. The method according to claim 1 or 2, wherein in step (d), the set temperature of the hair straightener is 160°C or higher.

8. A hair treatment agent used in step (b) of the method according to claim 1 or 2, comprising an organic acid and having a pH of less than 3.0.

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