JP2017072397A - Functionality evaluation method for cosmetic using hair keratin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating objectively the effect and the whole use feeling of a cosmetic, without using a panel or an animal skin.SOLUTION: A hair keratin protein solution obtained by dissolving hair with a protein modifier and a reducer is brought into contact with a developing solution so as to be solidified, and a keratin film obtained by being dried thereafter is brought into contact with a cosmetic, and a physical change generated by penetration of the cosmetic into the keratin film is measured, to thereby evaluate functionality of the cosmetic.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for evaluating the functionality of a cosmetic, and more particularly to a method for evaluating the functionality of a cosmetic using a film containing hair-derived keratin protein as a main component.

  Keeping the skin smooth and protecting it from drying is the most expected and important function for skin care cosmetics. In addition, it is known that the feeling of use at the time of application, specifically, the speed of familiarity with the skin and the feeling received by the finger are important indicators when the user selects cosmetics.

  As a method for evaluating the function (or effect) of cosmetics and the feeling of use, an actual use test in which a specialized panel actually uses cosmetics to evaluate is widely used. In particular, the effect of smoothing the skin and the feeling during use at the time of application are difficult to quantify with a measuring instrument, and are currently almost dependent on actual use tests. However, in the actual use test, the difference in the constitution and taste between the panels has a great influence, so that there is a problem that the number of tests has to be increased to obtain a reliable result, and the cost becomes high.

Therefore, a method for evaluating cosmetics using animal skin instead of the panel is also performed. For example, in Patent Document 1, it is obtained by applying lotion from the contact angle of the lotion dripped onto the skin of the minipig and the result of fluorescence microscope observation of the application state of the lotion to which the fluorescent substance is added. A method for predicting and evaluating smoothness and familiarity is shown.
However, an evaluation method using animal skin is not necessarily a preferable method from the viewpoint of animal protection. Therefore, many pseudo skins mainly composed of non-biological materials have been developed.

  The pseudo skin used for the evaluation of cosmetics can be obtained by performing various surface modifications and / or surface treatments on a film mainly composed of a polymer such as urethane, silicone, nylon, etc. The mainstream is a shape that approximates human skin. As a representative of such artificial skin, the surface of a film mainly composed of a urethane elastomer is blended with a surfactant or wax to reduce the free energy of the film surface, or a film forming agent is coated or graft polymerized. By doing so, bioskin (registered trademark, manufactured by Beaulux Co., Ltd.) that realizes hydrophobicity close to human skin and reproduces wrinkles on the surface of human skin by applying a texture treatment or the like. In addition, a film mainly composed of vinyl chloride (supplera (registered trademark), manufactured by Idemitsu Technofine Co., Ltd.), silicone elastomer (for example, JP-A-9-56468), or nylon (for example, JP-A-2001-48789). There is also known a pseudo-skin that has been subjected to groove processing or uneven processing imitating the skin groove of human skin. In addition, a thin film obtained by pouring a urethane film-forming agent into a silicone replica modeled on the human skin surface is laminated on a pseudo flesh mainly composed of a urethane polymer to faithfully reproduce the shape of the human skin surface. A simulated skin reproduced in (2) has also been reported (Patent Document 2).

  Since these artificial skins have the same shape, texture, and wettability as human skin, and the applied cosmetics can be well retained on the surface, evaluation of the colorability and detergency of cosmetics etc. (For example, Patent Document 2). However, it is rarely used for other evaluations (for example, the UV shielding effect of Patent Document 3), especially for evaluating the effect of smoothing the skin, the barrier effect from drying, and the feeling of use at the time of application. It is considered unsuitable. These effects are basically exhibited by the penetration of cosmetics into the skin, and the feeling of use at the time of application depends on the penetration of the cosmetics, whereas the penetration of the cosmetics is substantially in the pseudo skin. Because it does n’t happen.

  Under such circumstances, there has been a demand for a method that can objectively evaluate the effects and the feeling of use that are exhibited by penetrating the skin without using panels or animal skin.

JP 2011-53068 A JP-A-11-169390 JP 2002-48789 A JP 2002-332357 A

Fujii T., et al, Biol. Pharm. Bull., 27: 1433-1436, 2004

  The present invention has been made in view of the problems of the prior art, and an object thereof is to provide a method for objectively evaluating the effects of cosmetics and the overall feeling of use without using panels or animal skin.

  As a result of intensive studies by the inventor in order to achieve the above object, the hair keratin protein solution in which the hair is dissolved with a protein denaturant and a reducing agent is brought into contact with a developing solution to be solidified and then dried. It was found that the resulting keratin film repels water on the surface of the keratin film as well as human skin and repels water, preferentially permeating the cosmetic into the interior rather than water. And the properties of the keratin film are changed by penetration of cosmetics, smoothness and water resistance are given, and furthermore, the speed of penetration at the time of application and the frictional force received by the finger are different for each cosmetic. The headline and the present invention have been completed.

That is, according to the present invention, the hair keratin protein solution in which the hair is dissolved with a protein denaturant and a reducing agent is brought into contact with a developing solution to be solidified and then dried, and then the keratin film obtained by drying is brought into contact with the cosmetic. There is provided a method for evaluating the functionality of a cosmetic, wherein the functionality of the cosmetic is evaluated by measuring a physical change caused by the cosmetic permeating the keratin film.
In the method for evaluating the functionality of the cosmetic, after applying the cosmetic to the keratin film and infiltrating it, the coefficient of friction in the applied region is measured, and the average value of the coefficient of friction and the fluctuation width are used as indices for the cosmetic. A method of evaluating the effect of smoothing the skin of the material is included.
In addition, a method of evaluating the barrier effect from drying of the cosmetic by measuring the change with time of the contact angle of water in the application region after applying the cosmetic to the keratin film and infiltrating it is also included.
Furthermore, a method of evaluating the ultraviolet shielding effect of the cosmetic by measuring the ultraviolet transmittance in the application region after applying and penetrating the cosmetic to the keratin film is also included.
Further, after dripping the cosmetic on the keratin film, the change with time of the contact angle of the cosmetic is measured, and the permeability of the cosmetic to the skin is evaluated using the speed of decrease of the contact angle as an index. The method of doing is also included.
In the functionality evaluation method for a cosmetic according to the present invention, the physical change may be a physical change that occurs in a process of applying the cosmetic with a finger on the keratin film.
The physical change may be a time-dependent change in strain or shear force generated on the finger, and the time until the strain or shear force reaches the maximum value from the start of application is used as an index to quickly adjust the skin familiarity with the cosmetic. Can be evaluated.
The physical change may be a coefficient of friction applied to the frictional force between the finger and the cosmetic, and the user's preference during application can be evaluated using the coefficient of friction.

  The present invention provides a method for objectively evaluating the effects of cosmetics and the overall feeling of use without using panels or animal skin. According to the evaluation method using the keratin film according to the present invention as pseudo skin, the effect exhibited by the penetration of the cosmetic into the skin, which has been difficult with the conventional evaluation methods using pseudo skin (for example, the skin The effect of smoothing, the barrier effect from drying, etc.) and the feeling of use at the time of application (for example, the speed of familiarity with the skin and the feeling received by the finger, etc.) can also be objectively evaluated.

It is the result of having analyzed the temporal change of the contact angle of water and cosmetics on the keratin film (precast film, soft postcast film) concerning the present invention (test example 1). It is the result of apply | coating an emulsion to the keratin film concerning this invention, and analyzing the time-dependent change of the contact angle of the water in an application part and a non-application part (Test example 2). A sample is apply | coated to the keratin film concerning this invention, the surface friction coefficient of an application part is measured, and the obtained MIU and MMD value are represented (Test Example 3). A sample is applied to the keratin film according to the present invention, and an ultraviolet absorption spectrum in the applied portion is represented (Test Example 4). It is the result of having analyzed the time-dependent change of the distortion and shear force which arise in a finger in the process of applying a sample to the keratin film concerning the present invention (test example 5). It is the result of having analyzed the friction coefficient concerning the frictional force which arises between a finger and cosmetics in the process of applying a sample to the keratin film concerning the present invention (test example 6).

Hereinafter, preferred embodiments of the present invention will be described.
The method for evaluating the functionality of a cosmetic according to the present invention is to bring the keratin film according to the present invention into contact with the cosmetic as a pseudo skin, and to measure and analyze the physical changes that occur. It is a method to evaluate. Note that the “functionality” of the cosmetic in this document includes the “effect” and “use feeling” of the cosmetic. In addition, “application” in this document refers to the act of spreading with a finger until almost the entire amount of cosmetic material penetrates into the object to be applied (pseudo skin, etc.) and the cosmetic material does not substantially remain on the object. Point to.
First, the keratin film that can be used in the present invention will be described in detail.

<Keratin film>
The keratin film according to the present invention is mainly composed of an intact keratin protein extracted from a cortex portion of hair, and the protein forms a network structure via an SS bond. It is a characteristic membranous structure. The keratin film was invented by the present inventor, and is a protein solution obtained by treating hair with a denaturing agent and a reducing agent (a solution containing keratin protein as a main component. Hereinafter, in this document, hair keratin protein solution and Produced by exposing the keratin protein to insolubility rapidly by exposing it to a low ionic strength solution (sometimes referred to as a developing solution in this document). (Patent Document 4, Non-Patent Document 1). The manufacturing method will be described below.

<Method for producing keratin film>
In order to extract the keratin protein group which comprises it from hair, a protein denaturant is used. The hair sample used for preparing the keratin film may be degreased in advance. Although the method of degreasing is not limited, For example, processing with the mixed solvent of chloroform and methanol etc. are mentioned.
The protein denaturant is preferably a urea compound, and examples thereof include urea, thiourea, and derivatives thereof. It is preferable to use a mixture of one or more of these urea-based protein denaturants. More preferably, urea and thiourea are mixed and used. When using a mixture of urea and thiourea, the mixing mass ratio is preferably 5: 1 to 1: 2 (urea: thiourea). If the mixing ratio of thiourea is less than the above range, the protein denaturing action may be inferior, and if it exceeds the above range, the extraction rate of the keratin protein group tends to decrease.

  The concentration of the protein denaturant in the hair sample treatment solution is preferably 30 to 70% by mass. If the amount is less than 30% by mass, the extraction rate of the keratin protein group tends to decrease, and even if it is used in excess of 70% by mass, the effect of improving the extraction rate by increasing the amount is not recognized, and the hair sample treatment solution In some cases, the viscosity of the resin becomes high, and workability may deteriorate. Here, the “hair sample treatment solution” means a hair keratin protein solution comprising a hair sample and a protein denaturant, and a mixed solution in the production process for extracting a keratin protein group, including a reducing agent described later. . As described above, by using a protein denaturant, it is possible to efficiently dissolve and extract a keratin protein group from hair under mild conditions.

In preparing the keratin film used in the present invention, a reducing agent is used in combination with the protein denaturing agent. Examples of the reducing agent include thioalcohols such as 2-mercaptoethanol, dithiothreitol, and thioglycolic acid. These 1 type (s) or 2 or more types can be used in combination.
By using a reducing agent in combination with the protein denaturant, the extraction rate of the keratin protein group can be further improved. This is because the protein modifier denatures the strong keratin fiber structure, and then the reducing agent efficiently dissociates the strong S—S bond between the keratin proteins, and recombination in the hair sample treatment liquid hardly occurs. It is thought to do.

When the reducing agent is used in combination with a protein denaturant, the hair sample treatment solution preferably contains 0.5 to 40% by mass, more preferably 1 to 20% by mass. However, the said density | concentration can be suitably determined with the solubility in the hair sample processing liquid of the reducing agent to be used.
When the concentration of the reducing agent is less than 0.5% by mass, there is a tendency that the strong reductive cleavage of the S—S bond between the keratin proteins is not sufficiently performed, and when the concentration exceeds 40% by mass. The solubility of the keratin protein group in the hair treatment solution may be deteriorated.

The treatment time for obtaining the hair keratin protein solution depends on the treatment temperature, but is preferably 1 to 4 days. Moreover, it is preferable that processing temperature is 20-60 degreeC. If the temperature is lower than 20 ° C, the progress of the reaction is delayed and the efficiency is poor. If the temperature exceeds 60 ° C, the hair sample treatment solution exhibits alkalinity and is accompanied by side reactions such as peptide bond cleavage, substituent conversion, and crosslinking. There is a case.
The ratio of the hair sample to the hair sample treatment solution is preferably 1 to 100 mg hair sample / ml hair sample treatment solution.
After the keratin protein is sufficiently extracted from the hair sample treatment solution, the hair-extracted hair is removed by filtration to obtain a hair keratin protein solution.

In order to solidify or gel the hair keratin protein solution obtained by treating a hair sample with a protein denaturing agent and a reducing agent and filtering it, the developing solution is contacted. By this solidification or gelation, the film is formed as a film having a form suitable for the measurement method according to the present invention.
Examples of the developing solution include a modifying agent solution obtained by mixing a modifying agent such as trichloroacetic acid, guanidine hydrochloride, perchloric acid, and derivatives thereof, and a solvent such as water, physiological saline, and lower alcohol, and hydrochloric acid. And acidic solutions composed of acidic substances such as sulfuric acid, acetic acid, phosphoric acid and salts thereof, and one or more of these can be used. In the preparation of the keratin film used in the present invention, guanidine hydrochloride, a perchloric acid modifier or a perchloric acid solution obtained by mixing acetic acid and water, a guanidine hydrochloric acid solution, an acetic acid buffer solution, and an acetic acid solution as a developing solution. It is preferable that it is 1 type, or 2 or more types selected. Particularly preferred is an acetate buffer (pH 4.0) and / or an acetic acid solution.

The concentration of the denaturant solution used as the developing solution is preferably 10 to 60% by mass. The concentration of the acidic solution used as the developing solution is preferably 10 to 500 mM.
The developing solution has an action of lowering the ionic strength of the hair keratin protein solution, thereby causing a decrease in the solubility of the protein denaturant and reducing agent in the hair sample treatment solution. As a result, the solubility of the keratin protein group is reduced, and the SS bond between the keratin proteins is dissociated to form a -SH state. Solidification will proceed.

  As a method for bringing the hair keratin protein solution into contact with the developing solution and solidifying the keratin protein, any of the pre-cast method and the post-cast method developed by the present inventor may be used (Non-patent Document) 1). The pre-cast method is a method in which a developing solution is mixed with hair keratin protein in advance, and the mixed solution is cast into a container such as a petri dish filled with water. In the Post-cast method, a container such as a petri dish is filled with the developing solution in advance and a hair keratin protein solution is cast into the container (Forward method), or a petri dish to which a hair keratin protein solution is added in advance. The container includes a method of casting the developing solution (Reverse method).

As the developing solution by the Pre-cast method, an acetic acid solution can be suitably used, and in the Post-cast method, an acetic acid buffer is suitable as the developing solution.
As a reducing agent, 2-mercaptoethanol is suitable for use in the Post-cast method, and dithiothreitol is suitable for use in the Pre-cast method.
Further, the developing solution is preferably used at a mass ratio of 10 to 10,000 times that of the hair keratin protein solution. By bringing the developing solution into contact with the hair keratin protein solution within the above range, a thin film exhibiting an appropriate thickness can be prepared.
By these methods, the hair keratin protein can be solidified in the form of a thin film on the bottom surface of the petri dish or the like. In addition, an arbitrary plate-like structure (for example, a slide glass) is placed in a container such as the petri dish and the above operation is performed, and the hair keratin protein is solidified into a thin film on one surface of the plate-like structure. Also good.

  Thereafter, the petri dish or the plate-like structure is washed with the developing solution. The number of times of washing is not particularly limited, but is preferably about 1 to 5 times. After washing, the solution is removed and dried to obtain a product in which a keratin film is laminated on the petri dish bottom surface or one side surface of the plate-like structure (hereinafter sometimes referred to as a keratin film molded product). The drying method is not particularly limited, and examples thereof include standing at room temperature free from dust.

In this document, among the post-cast methods, the keratin films manufactured using the forward method and the reverse method are referred to as a hard postcast film and a soft postcast film, respectively. The keratin films manufactured by the pre-cast method are referred to as precast films. Call. These three types of keratin films all have a smooth surface and are reasonably soft, and both the texture and feel are close to those of human skin. In addition, on the surface, like human skin, it has the property of repelling water and blending with cosmetics. The precast film can preferentially permeate cosmetics over water, and the soft postcast film has a property of selectively permeating cosmetics without substantially passing water.
In the method for evaluating the functionality of a cosmetic according to the present invention, any of the three types of keratin films can be suitably used. Particularly preferred are soft postcast films and precast films, and most preferred are soft postcast films. It is a film. This is because the soft postcast film is more similar to the stratum corneum of human skin in that it does not substantially penetrate water than the other two keratin films.

<Method for evaluating the functionality of cosmetics>
In the method according to the present invention, the keratin film and the cosmetic are brought into contact with each other, and the physical change caused by the penetration of the cosmetic into the keratin film is measured and analyzed. evaluate. This effect is not limited to the makeup effect (colorability) of cosmetics and easy to clean (cleanability), but it has been difficult with conventional methods using artificial skin (cosmetics) penetrate into the skin. It is also possible to objectively evaluate the effects (eg, the effect of smoothing the skin and the barrier effect from drying) and the effect of being greatly affected by penetration (eg, the ultraviolet shielding effect). it can.

  Among these, for the paintability and cleanability of cosmetics, the same method as the conventional method using pseudo skin (for example, Patent Document 2) can be used, but the keratin film of the present invention is used as pseudo skin. As a result, it is possible to obtain an evaluation result that is closer to actual use in consideration of the permeation amount of the cosmetic.

  With regard to the effect of smoothing the skin and the barrier effect from drying, the physical properties described below are applied to the film after applying the cosmetic to the keratin film according to the present invention, and preferably leaving it to stand for a certain period of time for drying. It can be evaluated by measuring changes in the environment.

The effect of smoothing the skin As the physical change, the friction coefficient was measured in the region where the cosmetic was applied, and the average value of the obtained friction coefficients (hereinafter referred to as the average friction coefficient, abbreviated as MIU in this document) In some cases, the effect of smoothing the skin of the cosmetic can be evaluated.
The friction coefficient (μ) means that the two surfaces F and F of the friction force acting on the contact surface of the two objects (in the present invention, the contact surface of the friction measurement probe and the keratin film) are pressed vertically. It is a ratio (μ = F / P) to the magnitude P of the force (vertical load) that is being measured, and the average friction coefficient (MIU) is measured while the friction measurement probe moves in the region of the keratin film. It is the average value of the values (friction coefficient) obtained by doing. Therefore, the average friction coefficient in the present invention is expressed by the following mathematical formula (1).

(In the formula, L represents the moving distance of the probe, and μ represents the coefficient of friction)

  Further, the deflection width of the average friction coefficient is a value indicating the degree of variation in the measured friction coefficient, and can be represented by, for example, the following mathematical formula (2). In this document, the value represented by the following mathematical formula (2) is referred to as the variation of the average friction coefficient and may be abbreviated as MMD.

(In the formula, L represents the moving distance of the probe, and μ represents the coefficient of friction)

  The coefficient of friction can be measured using a general-purpose device, and particularly preferably, a friction sensation tester of a type that measures a frictional force (generated between the test substance) while the probe slides on the test substance surface. It is. An example of such a friction tester is a friction tester KES-SE (manufactured by Kato Tech Co., Ltd.). By using the tester, the measurement of the friction coefficient and the calculation processing of MIU / MMD are automatically performed. Can be done.

The MIU value is an index of the smoothness of the test substance surface, and the smaller the value, the smoother the value. The value of the MMD is known to correlate strongly with the goodness of finger sliding when a human traces the surface of the test substance with a finger, and the smaller the value, the better the finger sliding.
Therefore, the MIU and / or MMD values obtained in the keratin film region where the cosmetic is not applied or the keratin film region where the control substance (for example, water) is applied, and the keratin film region where the cosmetic is applied By comparing the value, the effect of smoothing the skin of the cosmetic can be evaluated as a numerical value.

-Penetration into the skin As the physical change, the penetration of the cosmetic into the skin can be evaluated by measuring the change over time in the contact angle of the cosmetic dropped onto the keratin film. It can be evaluated that the cosmetic with a faster decrease in the value of the contact angle has higher permeability to the skin. Note that the rate of decrease of the value is the rate of decrease of the contact angle per unit time or until the contact angle becomes 0 degree (that is, until the remaining amount of cosmetic on the keratin film is substantially eliminated). It can be evaluated as the time it takes.

-Barrier effect from drying To evaluate the barrier effect from drying of the cosmetics by measuring the change with time of the contact angle of water in the application area for the keratin film that has been applied and infiltrated with the cosmetics. Can do. It is evaluated that the cosmetic with a smaller rate of decrease in the applied area compared to the value of the water contact angle in the cosmetic non-applied area has a higher effect of imparting water resistance to the skin, that is, a barrier effect from drying. can do. This evaluation method is particularly suitable for evaluating the barrier effect of emulsions and creams.

-UV shielding effect As the physical change, after applying and permeating the cosmetic on the keratin film, measuring and analyzing the UV transmittance of the keratin film before and after coating, the ultraviolet shielding effect of the cosmetic Can be evaluated. In general, cosmetics having an ultraviolet shielding effect are blended with an oil-soluble component and a water-soluble base mainly with an ultraviolet shielding component. In the measurement of UV transmittance, the measured value is low when the UV shielding agent remains as a uniform coating film on the support (= keratin film in the method of the present invention) after the water-soluble base rapidly permeates and diffuses. Tend to be. In the keratin film according to the present invention, the water-soluble base quickly permeates into the film, and the ultraviolet shielding component easily forms a uniform coating film on the film surface, so that stable measurement is possible.
Therefore, by using the method according to the present invention, it is possible to evaluate the ultraviolet shielding effect in consideration of penetration and absorption of cosmetics.

・ Fastness of skin familiarity As the physical change, the time-dependent change of strain or shear force generated in the finger during the process of applying the cosmetic is measured, and the time until the value reaches the maximum value is used as an index. You can evaluate the speed of skin familiarity. In the process of applying the cosmetic, first, fluid friction occurs between the finger and the cosmetic, and when the total amount of the cosmetic penetrates into the keratin film, the fluid friction changes to boundary friction between the finger and the keratin film. Thus, the strain and shear force generated in the finger reach a maximum value. It is known that the user feels “the cosmetics are familiar with the skin” when the fluid friction changes to the boundary friction. Therefore, cosmetics with a shorter time from the start of application to the change to boundary friction (i.e., until the strain or shear force generated in the finger reaches the maximum value) are evaluated as cosmetics with faster skin familiarity. be able to.
The strain can be measured by, for example, a pressure and acceleration sensor of a type attached to a finger. Examples of the sensor include a haplog (HapLog, registered trademark, manufactured by Kato Tech Co., Ltd.), a motion detection sensor, a motion detection device (see JP-A-2014-142206), and the like.
The shear force can be easily measured by fixing the keratin film on a device capable of measuring the force generated in the triaxial direction, for example, a force plate (manufactured by Tech Gihan Co., Ltd.). Can be measured.

・ Finger feel during application The finger feels during application by measuring the change over time of the coefficient of friction applied to the friction force generated between the finger and the cosmetic during the cosmetic application process as the physical change. Can be evaluated. The friction coefficient is preferably analyzed as a change over time or an average value as a coefficient of fluid friction until the entire amount of the cosmetic penetrates into the keratin film. Since the user's preference for the strength of the resistance received by the finger varies depending on the user, it is impossible to make an unambiguous judgment on the friction coefficient (for example, a judgment that the higher the value is, the better). The user's preference can be quantified.
The coefficient of friction can be measured easily by fixing the keratin film on a force plate (manufactured by Tec Engineering & Sales Co., Ltd.) and applying it.

  If the method concerning this invention is used, it is possible to evaluate the functionality about the cosmetics of the wide dosage form except solid (a powder form is included). Particularly suitable dosage forms include liquids, emulsions, gels, creams, etc., and can be suitably used for functional evaluation of lotions, emulsions, cosmetics, creams and the like.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples. In addition, the numerical value in an Example represents the mass% unless there is particular description.
In the following test examples, a keratin film molded article in which a keratin film (precast film or soft postcast film) was laminated as a thin film on a slide glass was used as the keratin film. The manufacturing method will be described below.

[Production of keratin film molded product]
-Preparation of hair protein solution For 60 g of human hair with no history of chemical treatment such as perm, bleach, etc., 100 ml of Shindai method solution (2.6 M thiourea, 5 M urea, 250 mM dithiothreitol, 25 mM Tris-HCl, pH 8. 5) was added and incubated at 50 ° C. for 24 hours. Thereafter, filtration and centrifugation (12,000 × g, 15 minutes) were performed, and the supernatant was collected to obtain a hair keratin protein solution.

-Preparation of precast film molded article A slide glass was placed on the bottom of a culture petri dish (made of polystyrene), and the petri dish was filled with water. 6 ml of 100 mM acetic acid aqueous solution was added to and mixed with 3.5 mg of the hair keratin protein solution, and the resulting mixed solution was gently cast into the petri dish. After the hair keratin protein solidified, the developing solution containing distilled water was changed several times, and the solution in the gel was replaced with distilled water. Finally, distilled water was removed and the product was sufficiently dried in a box containing silica gel to obtain a precast film molded article.

-Preparation of soft postcast film molded article A slide glass was placed in a culture petri dish (made of polystyrene) and filled with a 40 mM magnesium chloride solution (= developing solution). The hair keratin protein solution was cast on the petri dish and allowed to stand for 40-60 minutes, and then washed with deionized water for 30-36 hours. Then, the soft post-cast film molded article which is translucent and elastic was obtained by making it dry naturally.

  The “slide glass” used as a control in Test Examples 1 and 4 is of the same standard as the slide glass used for producing the keratin film molded product.

[Test Example 1: Evaluation of cosmetic permeability]
The following sample (lotion 1-3 or water) is dropped on the surface of two types of keratin film molded products (precast film, soft postcast film) and slide glass (control), and a fully automatic contact angle meter (DM-701, The change in contact angle over time was measured using Kyowa Interface Science Co., Ltd. The amount of the sample dropped is 40 μl for the precast film and 20 μl for the soft postcast film and the slide glass. As will be described later, since the sample penetrated quickly in the precast film, the analysis was performed with the capacity increased. The results are shown in FIG.

<Prescription and characteristics of lotion>
(Toner 1): Fresh and sensation that penetrates quickly into the skin
Ingredient Amount (% by mass)
Glycerin 2
1,3-butylene glycol 0.5
Dipropylene glycol 0.5
Xanthan gum 0.02
Ethyl alcohol 3
Polyoxyethylene polyoxypropylene 2-decyltetradecyl ether 0.1
Ion exchange water Residue (skin lotion 2): Moist, feel that slowly penetrates skin
Ingredient Amount (% by mass)
Glycerin 4
1,3-butylene glycol 4
Dipropylene glycol 5
Hydroxyethyl cellulose 0.08
Ethyl alcohol 3
Polyoxyethylene polyoxypropylene 2-decyltetradecyl ether 0.1
Ion-exchanged water Residue (skin lotion 3): Feels like a tiny, penetrating skin
Ingredient Amount (% by mass)
Glycerin 6
1,3-butylene glycol 0.5
Dipropylene glycol 5
Xanthan gum 0.02
Ethyl alcohol 3
Polyoxyethylene polyoxypropylene 2-decyltetradecyl ether 0.1
Ion exchange water

  In FIG. 1, when paying attention to the contact angle immediately after dropping, it can be seen that in any glass slide, any sample is as small as about 30 degrees or less, so that these samples are similarly adapted to the glass surface. In contrast, the precast film and the soft postcast film have greatly different contact angles between cosmetics and water (contact angle of water: 100 degrees or more, contact angle of lotion: both are about 55 degrees or less). It became clear that the surface of the keratin film was compatible with lotion but repels water.

Next, paying attention to the change with time of the contact angle, it can be seen from the results of the slide glass that the water tends to volatilize in the order of the lotions 1, 3, and 2, and the water is most difficult to volatilize. This is because any sample does not penetrate into the glass on the slide glass, and the contact angle decreases according to the easiness of volatilization of each sample.
On the other hand, in the precast film, the contact angle of the skin lotion 1-3 decreases rapidly, and after 80 seconds from the dripping, the contact angle of any lotion becomes 0 degree, that is, almost all of the amount is in the film. It became clear that it penetrated. Moreover, since the contact angle of water also decreased earlier than on the slide glass, it was shown that water can penetrate into the precast film.
On the other hand, in the soft postcast film, there is no significant difference in the decrease rate of the contact angle of water compared with that on the slide glass, and it is considered that water hardly penetrates into the soft postcast film. In contrast, the contact angle of the skin lotion tended to decrease faster than on the slide glass, indicating that it could penetrate into the film.

  Therefore, in precast film, lotion and water quickly penetrate into the interior, but lotion is much easier to penetrate than water, and soft postcast film does not penetrate water but lotion It became clear that it penetrated.

  The stratum corneum of normal human skin is impermeable to water but is permeable to cosmetics, and this selective permeability prevents the skin from drying out. This function is called a stratum corneum barrier function, and it is known that when the barrier function is lowered, moisture evaporates from the inside through the stratum corneum, and dry skin, dermatitis, etc. are easily developed.

  Therefore, from the above results, it was shown that the keratin film according to the present invention can be a stratum corneum model of human skin.

[Test Example 2: Evaluation of barrier function from drying]
Next, using the keratin film according to the present invention, the effect of applying the emulsion was analyzed.
Two types of keratin film molded products (precast film, soft postcast film) were coated with 0.1 g of the emulsion having the following formulation and allowed to dry at room temperature for 1 hour. Thereafter, 20 μl of ion-exchanged water was dropped onto the coating part, and the change with time of the contact angle was measured using a fully automatic contact angle meter (DM-701, manufactured by Kyowa Interface Science Co., Ltd.). As a control, the contact angle of water in the non-emulsified part was also measured. The results are shown in FIG.

<Emulsion prescription>
Ingredient Amount (% by mass)
Glycerin 10
1,3-butylene glycol 5
Dipropylene glycol 5
Polyethylene glycol 1
Carboxyvinyl polymer 0.1
Caustic soda appropriate amount isostearic acid 0.5
Stearic acid 0.5
Dimethylpolysiloxane 3
Glyceryl triisooctanoate 5
Hydroxyethyl cellulose 0.1
Ion exchange water

As shown in FIG. 2, in any keratin film, the contact angle immediately after dropping of water, which was about 100 degrees or more in the non-coated part, was about 60 degrees (precast film) or about 48 degrees in the emulsion coated part. (Soft postcast film) was significantly reduced. That is, as a result of the penetration of the emulsion, it can be seen that the surface of the keratin film has changed from the property of repelling water to the property of adapting to water. Furthermore, in the precast film, the decrease in the contact angle of water with the passage of time at the coating part becomes very gradual, making it difficult for water to penetrate inside the film, that is, imparting remarkable water resistance to the precast film. It was shown that
In addition, when the present inventor applied an emulsion with a higher oil content, not only the precast film but also the soft postcast film, the decrease in the water contact angle with time was moderate. I have confirmed.

  From these results, it was shown that when the keratin film according to the present invention is used, the water resistance imparted by the application of the cosmetic, that is, the barrier effect from the drying exhibited by the cosmetic can be evaluated.

[Test Example 3: Evaluation of the effect of smoothing the skin]
Subsequently, the effect of smoothing the skin of the cosmetic was evaluated.
A sample (a lotion 1-3 used in Test Example 1 and an emulsion used in Test Example 2) was applied to two types of keratin film molded products (precast film, soft postcast film), and left to dry at room temperature for 1 hour. I let you. 0.2 g of each lotion and 0.1 g of emulsion were applied to the precast film, and 0.1 g of each lotion and 0.1 g of emulsion were applied to the soft postcast film. Then, the friction coefficient of the application part and the non-application part was measured using the friction tester KES-SE (made by Kato Tech Co., Ltd.) (number of tests (N) = 3), and MIU and MMD values were calculated. The results are shown in FIG.

  From FIG. 3, in any keratin film, the MIU value of the emulsion application part was significantly lower than the MIU values of the non-application part and the lotion application part. Therefore, it can be seen that the application of the emulsion imparted good finger sliding to the keratin film. And MMD value was much lower in the lotion and the emulsion application part than in the non-application part in any keratin film. Therefore, it was shown that the surface of the keratin film becomes very smooth by applying the lotion or the emulsion. Furthermore, in the soft postcast film, the MMD value of the emulsion application part is much lower than the MMD value of the lotion application part. Therefore, when the soft postcast film is used, the difference in the effect of smoothing the skin It was revealed that can be evaluated with higher sensitivity.

From the above results, it was shown that by using the keratin film according to the present invention, the effect of smoothing the skin produced by the cosmetic can be evaluated by measuring the MIU and / or MMD value after the cosmetic application.

[Test Example 4: Evaluation of UV shielding effect]
Furthermore, the UV protection effect of cosmetics was evaluated.
The soft post-cast film molded product was coated with an ultraviolet shielding component-containing cosmetic having the following formulation (0.01 g or 0.05 g) and allowed to dry at room temperature for 1 hour. Thereafter, an ultraviolet absorption spectrum was measured using a spectrophotometer (HITACHI U-350, manufactured by Hitachi, Ltd.) (5 times), and an average value (average measurement value of the ultraviolet absorption spectrum) was calculated. As a control, the ultraviolet absorption spectrum in the cosmetic non-application part and the ultraviolet absorption spectrum of the slide glass were also measured. The results are shown in FIG.

<Prescription of UV shielding component-containing cosmetics>
Ingredient Amount (% by mass)
Octyl methoxycinnamate 5
Bisethylhexyloxyphenol methoxyphenyl triazine 2
1,3-butylene glycol 7
Carboxyvinyl polymer 0.1
Acrylic acid / alkyl methacrylate copolymer 0.1
Caustic soda appropriate amount Dimethylpolysiloxane 5
Ethyl alcohol 10
Poly (oxyethylene / oxypropylene) methylpolysiloxane copolymer 1
Isoparaffin 1
Ion exchange water

FIG. 4A shows the absolute value of the logarithm of the value for each wavelength calculated by dividing the average measured value of the ultraviolet absorption spectrum of the keratin film by the average measured value of the ultraviolet absorption spectrum of the slide glass alone in the UV shielding component-containing cosmetic application part. Value. From this result, it has been clarified that the keratin film itself has an ultraviolet absorbing ability mainly in the vicinity of 290 nm. The keratin protein contains an amino acid capable of absorbing ultraviolet rays such as tryptophan like the skin stratum corneum. In this respect, the present method can be said to be an evaluation method imitating the stratum corneum.
FIG. 4B shows the logarithm of the value for each wavelength calculated by dividing the average measurement value of the ultraviolet absorption spectrum of the keratin film in the cosmetic coating part containing the ultraviolet shielding component by the average measurement value of the ultraviolet absorption spectrum in the cosmetic non-application part. Is the absolute value of. The larger the value, the higher the ultraviolet shielding effect. From this result, it was shown that the ultraviolet shielding effect is increased depending on the amount of the cosmetic applied, and that the absorption characteristics for each wavelength can be confirmed.

  From the above results, it was shown that the UV protection effect of cosmetics can be evaluated by using the keratin film according to the present invention.

[Test Example 5: Evaluation of speed of skin familiarity]
Subsequently, the keratin film according to the present invention was used to evaluate the feeling of use when applying cosmetics. First, the “fastness of skin familiarity at the time of application”, which is emphasized by the user, was examined.

A precast film or a soft postcast film was fixed on a force plate (manufactured by Tec Co., Ltd.), and 40 μl (precast film) or 20 μl (soft postcast film) of the following sample was dropped onto the film. As a control, 20 μl of the sample was also dropped on a force plate (= specifically on an acrylic plate). Two specialist panels wearing a motion detection sensor and a motion detection device (Japanese Patent Application Laid-Open No. 2014-142206) applied the sample with their fingers, and measured the strain generated on the left and right sides of the finger during the application process. The difference in strain generated on the left and right side surfaces was calculated, and the change with time is shown in FIGS.
Further, the force generated in the triaxial direction during the coating process was measured with the force plate, the shearing force was calculated, and the change with time is shown in FIGS.
Further, 40 μl of the sample was applied to the inner side of the upper arm on a specialized panel on which the motion detection sensor and the motion detection device were mounted on the finger, and the difference in strain generated on the left and right sides of the finger during the application process was calculated (FIG. 5A).

<Sample prescription>
Ingredient Amount (% by mass)
Glycerin 10
Hydroxyethyl cellulose 0.1
Ion exchange water

As shown in FIG. 5A, when the cosmetic is applied to the inner side of the human forearm, the difference in strain between the left and right sides of the finger increases as the cosmetic penetrates into the skin, and the maximum value is about 45 seconds after the start of application. Reached. Therefore, it was found that when the cosmetic was applied to human skin, a feeling of use that “the cosmetic became familiar with the skin” was obtained after about 45 seconds.
On the other hand, when the cosmetic is applied to the acrylic plate, the volume reduction due to the penetration of the cosmetic does not occur, so the difference in strain between the left and right sides of the finger does not become larger than when the application is started. It was found that even after 90 seconds from the start, the feeling of “familiar with the skin” was not obtained (FIG. 5B).
On the other hand, when the cosmetic was applied to the precast film, the difference in strain gradually increased after the start of application, and reached the maximum value after about 80 seconds. Therefore, when the said cosmetics were apply | coated to the precast film, it became clear that the usability | use_feeling "familiar with the skin" was acquired after about 80 second (FIG. 5C).

  Similarly, in the measurement of the shearing force, the acrylic plate did not show an increase in the shearing force with time (FIG. 5D), but in the precast film, the shearing force reached the maximum value after about 80 seconds and “ It was shown that the feeling of use was “familiar” (FIG. 5E).

  From the above results, when the keratin film according to the present invention is used, the time until the strain or shear force generated on the finger reaches the maximum value in the process of applying the cosmetic is measured, so that the skin becomes familiar with the skin. It was shown that it can be evaluated.

[Test Example 6: Evaluation of the feel of a finger during application]
Subsequently, an attempt was made to evaluate the feel received by the fingers during application.
A precast film or a soft postcast film was fixed on a force plate (manufactured by Tec Co., Ltd.), and the following samples were dropped on each film. 6 professional panelists apply the cosmetics with their fingers, and measure the vertical force (FIG. 6A) and horizontal force (FIG. 6B) generated in the application process to calculate the friction coefficient (FIG. 6C). The change with time was graphed. And the average value of the friction coefficient in 5-20 seconds (in the case of a non-application part) or 5-40 seconds (when water or a base is apply | coated) from the start of application | coating is calculated (FIG. 6D), and also in all the panels. The average value was calculated (FIG. 6E).

<Sample>
Water / Base 1: 10% glycerin aqueous solution Base 2: 10% glycerin, 0.1% hydroxyethyl cellulose-aqueous solution

From FIG. 6, the value of the friction coefficient differs depending on the sample to be applied (FIGS. 6C and D), and the same tendency was recognized in a plurality of panels (FIG. 6E). In other words, it has been found that the average value of the friction coefficient can be used as a value (specific to each cosmetic) representing the characteristics of the cosmetic.
Therefore, it was shown that the feeling that a finger receives at the time of application using the value of the friction coefficient can be quantified to evaluate the user's preference.

Claims (8)

A keratin film obtained by solidifying a hair keratin protein solution obtained by dissolving hair with a protein denaturant and a reducing agent with a developing solution, and then drying the solution;
Contact with cosmetics,
Evaluating the functionality of the cosmetic by measuring physical changes caused by penetration of the cosmetic into the keratin film,
Functionality evaluation method for cosmetics.   After the cosmetic material is applied to the keratin film and infiltrated, the friction coefficient in the application region is measured, and the effect of smoothing the skin of the cosmetic material is evaluated using the average value of the friction coefficient and the fluctuation width as an index. The method for evaluating the functionality of a cosmetic according to claim 1.   The cosmetic according to claim 1, wherein the cosmetic is applied to the keratin film and allowed to permeate, and then the barrier effect from drying of the cosmetic is evaluated by measuring a change with time of the contact angle of water in the application region. Method for evaluating the functionality of the fee.   The method for evaluating the functionality of a cosmetic according to claim 1, wherein the cosmetic is applied to and penetrates the keratin film, and then the ultraviolet shielding effect of the cosmetic is evaluated by measuring the ultraviolet transmittance in the application region. .   After dripping the cosmetic on the keratin film, measuring a change with time of the contact angle of the cosmetic, and evaluating the permeability of the cosmetic to the skin using the speed of decrease of the contact angle as an index. Item 2. A method for evaluating the functionality of a cosmetic according to Item 1.   The method for evaluating the functionality of a cosmetic according to claim 1, wherein the physical change is a physical change that occurs in the process of applying the cosmetic on the keratin film with a finger.   The physical change is the time-dependent change of strain or shear force generated in the finger, and the speed of skin familiarity of the cosmetic is evaluated using the time from the start of application until the strain or shear force reaches the maximum value as an index. The method for evaluating the functionality of a cosmetic according to claim 6.   The method for evaluating the functionality of a cosmetic according to claim 6, wherein the physical change is a coefficient of friction applied to the frictional force between the finger and the cosmetic, and the feel received by the finger during application is evaluated using the coefficient of friction. .