JP2007147342A - Evaluation method of external preparation for skin, and external preparation for skin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of evaluating objective feeling of use not requiring a panelist, in evaluation of an external preparation for skin. <P>SOLUTION: In this evaluation method of the external preparation for skin, a storage modulus and a loss modulus to a frequency of the external preparation for skin are measured by using a parallel plate, and a storage modulus curve and a loss modulus curve to the frequency are drawn, and the frequency at an intersection point between the storage modulus curve and the loss modulus curve is determined, and the external preparation for skin is evaluated by using the frequency and existence of an inflection point on the loss modulus curve near the intersection point as indexes. The method has a characteristic wherein, when the frequency at the intersection point is below 0.5 (Angular frequency/rad/s) and the inflection point on the loss modulus curve exists in the periphery within 10% of the intersection point, it is determined to be cosmetics having strong function for providing comfort when used. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for evaluating a skin external preparation and a skin external preparation determined to be comfortable by the evaluation method.

  In skin external preparations such as cosmetics, the feeling of use is a very important factor. It is said that, when used, the rubbing and spreading of cosmetics gives good stimulation to the skin, and this stimulation suppresses the sympathetic nerve and releases the mind and body from stress. As described above, “usability” is an important quality factor, but there are few objective measurement methods and evaluation methods for this, and it is the only dehydrogenation in saliva or blood before and after applying makeup. There is only known a method for evaluating the change in the amount of epiandrosterone as an index (see, for example, Patent Document 1), and the current situation is left to sensory evaluation. Regarding the evaluation method using the change in the amount of dehydroepiandrosterone as an index, although objective numbers can be ejected, there is a part that cannot be said to be objective in terms of using panelists. That is, development of a technique that can evaluate an objective feeling of use without using a panel has been desired.

  On the other hand, methods for evaluating physical properties of external preparations for skin by measuring the storage elastic modulus and loss elastic modulus of cosmetics using a parallel plate have already been performed. (For example, refer to Patent Document 2, Patent Document 3, and Patent Document 4) However, no mention has been made of the relationship between the physical property value and a preferable feeling of use. In addition, a method for evaluating a skin external preparation, which uses a parallel plate to measure the storage elastic modulus and loss elastic modulus with respect to frequency of the skin external preparation, and stores the storage elastic modulus curve and loss elastic modulus curve with respect to frequency. A method for evaluating an external preparation for skin, using the frequency of the intersection of the storage modulus curve and the loss modulus curve as a frequency, and using the frequency and the presence or absence of an inflection point in the loss modulus curve near the intersection as an index In the evaluation method, the frequency at the intersection is 0.5 (Angular frequency / rad / s) or less, and the inflection of the loss modulus curve is within 10% of the intersection. No topical skin preparation was known at all.

Japanese Patent Laid-Open No. 11-35597 JP 2004-043785 A JP 2005-112823 A JP 2003-038773 A

  The present invention has been made under such circumstances, and an object of the present invention is to provide a technique capable of evaluating an objective feeling of use without using a panel in the evaluation of an external preparation for skin.

In view of such a situation, the present inventors have sought for a technique capable of evaluating an objective feeling of use without using a paneler in the evaluation of a topical skin preparation. An evaluation method, using a parallel plate, measuring storage elastic modulus with respect to frequency and loss elastic modulus of the external preparation for skin, creating a storage elastic modulus curve and a loss elastic modulus curve with respect to frequency, and Obtaining the frequency of the intersection of the elastic modulus curve and the loss elastic modulus curve and evaluating the frequency using the skin external preparation evaluation method using the frequency and the presence or absence of an inflection point of the loss elastic modulus curve in the vicinity of the intersection as an index Thus, it was found that such an evaluation can be made, and the present invention has been completed. That is, the present invention is as follows.
(1) Evaluation method of external preparation for skin, measuring storage elastic modulus with respect to frequency and loss elastic modulus of skin external preparation using parallel plate, storage elastic modulus curve with respect to frequency and loss elastic modulus Creating a curve, obtaining the frequency of the intersection of the storage modulus curve and the loss modulus curve, and using the frequency and the presence or absence of an inflection point of the loss modulus curve in the vicinity of the intersection as an index, Evaluation method for external preparation for skin.
(2) When the frequency at the intersection is 0.5 (Angular frequency / rad / s) or less and an inflection point of the loss elastic modulus curve exists in the vicinity of 10% or less of the intersection, The method for evaluating an external preparation for skin according to (1), characterized in that the cosmetic is determined to be a highly effective cosmetic.
(3) The method for evaluating a skin external preparation according to (1) or (2), wherein the method is an evaluation method of an emulsifier type skin external preparation.
(4) In the external preparation for skin, using a parallel plate, the storage elastic modulus with respect to the frequency and the loss elastic modulus of the external preparation for skin are measured, and a storage elastic modulus curve and a loss elastic modulus curve with respect to the frequency are created, When the frequency of the intersection of the storage modulus curve and the loss modulus curve is obtained, and the frequency and the presence or absence of an inflection point of the loss modulus curve near the intersection are examined, the frequency at the intersection is 0.1 (Angular frequency / rad / s), and an inflection point of a loss elastic modulus curve exists in the vicinity of 10% or less of the intersection.
(5) The external preparation for skin according to (4), which is in an emulsifier form.
(6) The external preparation for skin according to (4) or (5), which is an external preparation for skin containing an organically modified clay mineral.
(7) The skin external preparation according to any one of (4) to (6), wherein the organically modified clay mineral is dimethyl distearyl ammonium chloride modified hectorite.

  ADVANTAGE OF THE INVENTION According to this invention, in the evaluation of an external preparation for skin, the technique which can evaluate the objective usability without using a paneler can be provided.

(1) Evaluation method for external preparation for skin of the present invention The evaluation method for external preparation for skin of the present invention uses a parallel plate to measure the storage elastic modulus with respect to frequency and loss elastic modulus of the external preparation for skin, A storage elastic modulus curve and a loss elastic modulus curve with respect to a frequency are created, a frequency is obtained from an intersection of the storage elastic modulus curve and the loss elastic modulus curve, and the presence or absence of an inflection point of the loss elastic modulus curve near the intersection. As an index. The parallel plate is a general method for measuring viscodynamics, and uses it to measure storage elastic modulus and loss elastic modulus, and capture the viscodynamic characteristics of the object to be measured from the relationship between these two indices. It is used for Such a parallel plate type viscodynamic property measuring apparatus is generally called a rheometer, and there is a commercially available product, and the storage elastic modulus, Loss modulus can be measured. As such a rheometer, for example, “DAR type universal rheometer” manufactured by Rheologicala, “stress control type rheometer AR500” manufactured by TA Instruments, etc. can be preferably exemplified. Such storage elastic modulus and loss elastic modulus are measured by changing the frequency and determining the change of these values. The X axis is the frequency and the Y axis is the storage elastic modulus (G ′) or the loss elastic modulus. Plot the coordinates (G ″) and draw a storage modulus curve and / or loss modulus curve. In the present invention, the external preparation for skin is evaluated based on the relationship between the response of the storage elastic modulus to this frequency and the response of the loss elastic modulus.

The relationship between the storage elastic modulus curve and the loss elastic modulus curve, and the relationship between the evaluation of the external preparation for skin, the location of the intersection of the two curves, the presence or absence of an inflection point in the shape of the loss elastic modulus curve, and the inflection point The position of is used as an index. That is, when the X-coordinate of the intersection of two curves, that is, when the frequency is small, specifically 0.5 or less, the structure of the external preparation for skin is stable, is not easily collapsed by rubbing, and has a long-time coefficient of friction. The rubbing can continue without changing, and this increases the comfort. Further, since the loss elastic modulus curve has a maximum value, that is, an inflection point in the vicinity of the intersection, the kinematic viscosity increases at the final point of abrasion, and the end point can be clearly recognized, and the end point is recognized as a fit. . That is, the external preparation for skin having such viscodynamic properties is a skin external preparation that feels fit last while giving a stable irritation for a long time. Such a stable scratching stimulus for a long time forms comfort for the object to be scratched. Moreover, it is preferable to draw a gentle curve in which these secondary curves are characterized by both G ′ and G ″ falling between 100 and 2000 Pa from the high frequency side to the intersection. This means that the resistance value is always constant with respect to the stress. Further, it is preferable that the value of G′−G ″ is at least 200 Pa, more preferably 300 Pa, when the frequency is 100 to 1 Angular frequency / rad / s. When this difference exists to some extent, the feeling of use is felt during the rubbing action. Note that the slope of the loss modulus curve is greatly different between the low frequency side and the high frequency side, and the point at which this slope changes greatly can be defined as the inflection point, but this numerical value can be easily obtained by the following method. I can do it. That is, as shown in the following steps.
Step 1: Sample several points on a curve with a frequency of 1 to 10 Angular frequency / rad / s, and create a primary correlation equation Y1 using these coordinates.
Step 2: Sampling several points on a curve having a frequency of 0.01 to 0.1 Angular frequency / rad / s, and using these coordinates, a primary correlation equation Y2 is created.
Step 3: Find the intersection of Y1 and Y2, and use the x coordinate as the frequency of the inflection point.

(2) Skin external preparation of the present invention The skin external preparation of the present invention has a frequency at the intersection of 0.1 (Angular frequency / rad / s) or less in the evaluation method, and within 10% of the intersection The inflection point of the loss elastic modulus curve exists in the vicinity of. In order to exhibit such viscodynamic properties, a dosage form in the form of phase inversion during spreading, such as an oil-in-water emulsifier, is not preferred, and the aqueous phase is dispersed in the structure of a pre-made oily gel. The emulsified form of the emulsified form is preferable. Specifically, the polyoxyalkylene-modified methylpolysiloxane has a gel structure formed by an organically modified clay mineral and a polyhydric alcohol so that the aqueous component is in the form of a water-in-oil emulsifier. Those dispersed with the aid of a surfactant such as are preferred.

1) Organically modified clay mineral The external preparation for skin of the present invention is characterized by containing an organically modified clay mineral as an essential component. Here, organic modification means that a part or all of the properties of an organic compound is made into a clay mineral by causing a part of the organic compound to form a strong or loose bond via a covalent bond or an ionic bond. This means that it is imparted to minerals. Examples of such modifications include a method of binding a quaternary amine group and an anion portion of a clay mineral, and a method of binding a carboxyl group and a cation portion of a clay mineral. A method of combining the group and the anion portion of the clay mineral is particularly preferable.

  Although it does not necessarily limit as a compound which has a quaternary amino group which modifies a clay mineral, The compound called quaternium is illustrated. Quotanium is a low molecular weight substituted quaternary ammonium salt, and is preferably a cosmetic raw material registered in International Standard Cosmetic Ingredients (INCI). Furthermore, the compound having a quaternary amino group that modifies the clay mineral is preferably a quaternium compound contained in a conventional external skin preparation among quaternium compounds. Preferred examples of the quaternium compound used in conventional external preparations for skin include stearyl trimethyl ammonium chloride and dimethyl distearyl ammonium chloride. Stearyl trimethyl ammonium chloride, dimethyl distearyl ammonium chloride and the like are preferable because they can form a stable water-in-oil emulsion structure together with clay minerals.

  On the other hand, as a clay mineral (unmodified clay mineral) modified with a compound having a quaternary amino group, any clay mineral contained in a conventional skin external preparation can be used without any particular limitation. Preferred clay minerals contained in conventional skin external preparations include smectite-type hectorite, bentonite and montmorillonite; kaolinite; illite; marine clay mineral (sea mud); desert rose clay mineral; Among these, bentonite, hectorite, montmorillonite or kaolinite which can stabilize the water-in-oil emulsion structure is preferably exemplified.

An example of a method for producing a clay mineral modified with a compound having a quaternary amino group contained in the external preparation for skin of the present invention will be described below.
The unmodified clay mineral is dispersed in a dispersion medium. The dispersant is preferably an aqueous solvent, and may be water. A compound having a quaternary amino group is further added to the dispersion containing the dispersed unmodified clay mineral and stirred well. The compound having a quaternary amino group may be added after being dissolved in water. The amount of the compound having a quaternary amino group to be added is preferably 0.1 to 20% by mass, and more preferably 0.5 to 15% by mass with respect to the amount of the dispersed unmodified clay mineral. This is because by taking such a configuration, a preferable feeling of use is exhibited in the emulsification system. After stirring, the dispersoid is filtered, dehydrated and dried to obtain the modified clay mineral in the present invention. Or the modified clay mineral in this invention can also be obtained by removing a dispersing agent by concentrating under reduced pressure without filtering a dispersoid, and making it dry. The obtained modified clay mineral is preferably pulverized to a desired size (preferably having a particle size of 1 to 1000 μm) and contained in the skin external preparation of the present invention.

  The modified clay mineral in the present invention can be prepared and used as described above, but a commercially available one can also be used. Some modified clay minerals on the market are used as external preparations for skin such as cosmetics. Preferable examples of commercially available modified clay minerals include dimethyl distearyl ammonium modified hectorite sold under the name “Benton 38V” by Elementis.

  In the skin external preparation of this invention, this component is contained preferably 0.5-10 mass%, More preferably, 1-5 mass% is contained. Such an ingredient works as an emulsifier within the above-mentioned content range, and at the same time, works together with N-acyl glutamic acid diester in the feeling of use at the time of application, making the person being applied feel comfortable and relaxing. And has the effect of relieving stress. Thereby, the bad influence to the skin by stress can be reduced and relieved.

2) Polyoxyalkylene-modified methyl polysiloxane Among these components, polyoxyalkylene-modified methyl polysiloxane is particularly preferable, and among them, polyoxyalkylene-modified methyl polysiloxane having a crosslinked structure. The crosslinked structure can be produced by adding vinylmethyldimethoxysiloxane at the time of polymerization and polymerizing the vinyl group after polymerization to construct a crosslinked structure. As the polyether structure constituting such polyoxyalkylene-modified methylpolysiloxane, a polyethylene glycol residue or a polypropylene glycol residue can be preferably exemplified, and a polyethylene glycol residue is particularly preferred. Such polyoxyalkylene-modified methyl polysiloxane has a commercial product, and such a commercial product can be purchased and used. Preferable examples of commercially available products include “silicone KF6017” (crosslinked polyethylene glycol-modified methylpolysiloxane) sold by Shin-Etsu Chemical Co., Ltd. This component has the effect of further stabilizing the emulsified structure formed by the organically modified clay mineral, which is the essential component, and reducing the feeling of use when the aqueous phase leaks out during rubbing on the skin during application. Improve. In order to achieve such an effect, the polyoxyalkylene-modified methyl polysiloxane is preferably contained in an amount of 1 to 10% by mass, more preferably 2 to 7% by mass.

3) N-acyl glutamic acid diester In order to adjust so that the inflection point of the loss modulus curve exists in the vicinity of 10% or less of the intersection point, it has affinity for both the organically modified clay mineral and the oil component. When the internal phase disappears due to abrasion and the gel structure is about to be broken, the internal phase and the organically modified clay mineral are cross-linked, and the component that resists the collapse of the emulsified structure may be included. preferable. Preferred examples of such components include N-acyl glutamic acid diesters. The acyl group constituting the component may be saturated or unsaturated, for example, 2-ethylhexanoyl group, lauroyl group, myristoyl group, palmitoyl group, stearoyl group, behenoyl group, oleoyl group, isostearoyl group, A linolenoyl group etc. can be illustrated suitably, A lauroyl group is especially preferable. In addition, the alkyl group constituting the dialkyl ester may be branched, straight chain, or cyclic, for example, octyl group, lauryl group, cetyl group, stearyl group, isostearyl group, behenyl group, octyldodecyl. Preferred examples include phytosteryl groups such as campesteryl group and sitosteryl group, and cholesteryl group. Specific examples of the compound include N-lauroyl-L-glutamate di (cholesteryl / behenyl / octyldodecyl), N-lauroyl-L-glutamate di (cholesteryl / octyldodecyl), N-lauroyl-L-glutamate di (phytosteryl). / Behenyl / octyldodecyl), N-lauroyl-L-glutamate di (phytosteryl / octyldodecyl) and the like can be preferably exemplified, and N-lauroyl-L-glutamate di (cholesteryl / octyldodecyl) can be particularly suitably exemplified. Such an N-acylated glutamic acid diester is obtained by condensing glutamic acid and acyl chloride in the presence of an alkali to form N-acyl glutamic acid, and then in the presence of a base or acid, optionally in the presence of a solvent, and dehydrating with the corresponding alcohol. It can be produced by condensation. N-acylated glutamic acid diesters can be synthesized in this way, but some are already commercially available as cosmetic raw materials, and such commercial products can be purchased and used. . As a particularly preferred commercial product, “Eldue PS203” (N-lauroyl-L-glutamate di (cholesteryl / octyldodecyl)) sold by Ajinomoto Co., Inc. can be exemplified. These components can be contained alone or in combination of two or more. The preferred content is 0.1 to 10% by mass, more preferably 1 to 5% by mass, based on the total amount of the external preparation for skin.

  The external preparation for skin of the present invention can be produced by appropriately adding an optional component for formulation to such a component and treating it according to a conventional method. The obtained external preparation for skin is measured for viscodynamic properties according to the above evaluation method, and it is judged whether or not it is suitable as an external preparation for skin of the present invention.

  Hereinafter, the present invention will be described in more detail with reference to examples, but it is needless to say that the present invention is not limited to such examples.

  In accordance with the formulation shown below, a cosmetic that is an external preparation for skin was prepared. That is, the ingredients (a), (b), (c), and (d) are heated to 80 ° C., the ingredients (a) and (d) are thoroughly kneaded, added to (c), diluted, and gradually added to the mixture with stirring. The mixture was emulsified, stirred and cooled to obtain a water-in-oil cosmetic 1 (anti-inflammatory pharmaceutical quasi-drug) as a skin external preparation.

  According to Table 2 shown below, an oil-in-water emulsified cosmetic 2 which is an oil-in-water emulsifier type skin external preparation was produced. That is, the components of A, B, and C are heated to 80 ° C., respectively, neutralized by adding B to A, and the mixture is gradually emulsified with stirring and emulsified, cooled with stirring and oil-in-water emulsifier. Shaped cosmetic 2 was obtained.

<Test Example 1>
For cosmetics 1 and 2, the storage elastic modulus and loss elastic modulus were measured using a “stress control rheometer AR500” manufactured by TA Instruments, and a storage elastic modulus curve and a loss elastic modulus curve were prepared. . The result is shown in FIG. Thus, in cosmetic 1, the frequency at the intersection is 0.098 (Angular frequency / rad / s) or less at 0.5 (Angular frequency / rad / s) by simple calculation, and is within 10% of the intersection. It is preferable to draw a gentle curve in which there is an inflection point of the loss elastic modulus curve in the vicinity and both G ′ and G ″ fall between 100 and 2000 Pa from the high frequency side to the intersection. This means that the resistance value is always constant with respect to the stress. Further, it can be seen that the value of G′−G ″ is at least 200 Pa when the frequency is 100 to 1 Angular frequency / rad / s. The cosmetic 2 cannot calculate the inflection point by simple calculation and does not satisfy this requirement. Therefore, cosmetic 1 is identified as the cosmetic of the present invention, and cosmetic 2 is identified as not belonging to the cosmetic of the present invention.

<Test Example 2>
40 panelists selected at random are grouped into 2 groups of 20 people so that there is no bias in the attributes, 1 group massages with cosmetic 1 and 1 group uses cosmetic 2 The saliva was collected before and after the massage, and the amount of plasterone sulfate in the saliva was quantified. Plasterone sulfate was quantified by an outsourced laboratory using a sandwich antibody method. From the quantification result, the rate of increase in plasterone sulfate (%) from the formula of (amount of plasterone sulfate after massage-amount of plasterone sulfate before massage) / (amount of plasterone sulfate before massage) x 100 Was calculated. The results are shown in Table 3. From this, it can be seen that the cosmetic of the present invention has an excellent feeling of use and makes it feel comfortable.

  In the same manner as cosmetic 1 in Example 1, cosmetic 3 was prepared according to Table 4 below. The storage elastic modulus and loss elastic modulus of this were measured, and a storage elastic modulus curve and a loss elastic modulus curve were prepared. This is shown in FIG. The inflection point calculated simply was 0.23, and it was found that this cosmetic 3 was also the cosmetic of the present invention. When this was evaluated by the same procedure as in Test Example 2 (n = 3), the rate of increase in plasterone sulfate was 39.1 ± 8%, confirming the effect of the cosmetic of the present invention. It can be seen that it is preferable to use polyoxyalkylene-modified methylpolysiloxane to strengthen the structure.

  The present invention can be applied to the evaluation and design of cosmetics.

It is a figure which shows the measurement result of the rheometer of the cosmetics 1 and 2 of Example 1. FIG. It is a figure which shows the measurement result of the rheometer of the cosmetics 3 of Example 2. FIG.

Claims (7)

This is a method for evaluating external preparations for skin, and measures the storage elastic modulus and loss elastic modulus with respect to frequency of the external preparation for skin using a parallel plate, and creates a storage elastic modulus curve and a loss elastic modulus curve with respect to frequency. Wherein the frequency of the intersection of the storage modulus curve and the loss modulus curve is obtained, and the frequency and the presence or absence of an inflection point of the loss modulus curve near the intersection are used as indices. Evaluation method. When the frequency at the intersection is 0.5 (Angular frequency / rad / s) or less and an inflection point of the loss elastic modulus curve exists in the vicinity of 10% or less of the intersection, an effect of providing comfort during use The skin external preparation evaluation method according to claim 1, wherein the skin external preparation is determined to be a high cosmetic. The method for evaluating a skin external preparation according to claim 1 or 2, wherein the method is an evaluation method for an emulsifier-type skin external preparation. In the external preparation for skin, the storage elastic modulus with respect to the frequency and the loss elastic modulus of the external preparation for skin are measured using a parallel plate, and the storage elastic modulus curve and the loss elastic modulus curve with respect to the frequency are prepared. The frequency at the intersection of the modulus curve and the loss modulus curve is obtained, and when the frequency and the presence or absence of the inflection point of the loss modulus curve near the intersection are examined, the frequency at the intersection is 0.5 (Angular frequency / rad / s), wherein the inflection point of the loss elastic modulus curve exists in the vicinity of 10% or less of the intersection. The external preparation for skin according to claim 4, which is in an emulsifier form. The skin external preparation according to claim 4 or 5, wherein the skin external preparation contains an organically modified clay mineral. The skin external preparation according to any one of claims 4 to 6, wherein the organically modified clay mineral is dimethyl distearyl ammonium chloride modified hectorite.

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