JP4719558B2 - Method for evaluating external preparation for skin and external preparation for skin - Google Patents

Description

The present invention relates to a method of evaluating the external preparation for skin.

  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 product, and only dehydration in the 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 released, there is a part that cannot be said to be sufficient in terms of objectivity 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 measuring the storage elastic modulus and loss elastic modulus of cosmetics by using a parallel plate type viscoelasticity measuring device and evaluating physical properties have already been performed (for example, Patent Document 2 and Patent Document 3). , See Patent Document 4). However, no mention has been made of the relationship between the physical property values and the preferred feeling of use. Also, using a parallel plate type viscoelasticity measuring device, measure the storage elastic modulus and loss elastic modulus for each frequency of the external preparation for skin, and create a storage elastic modulus curve and a loss elastic modulus curve for each frequency. In addition, a method for evaluating a topical skin preparation using the frequency at the intersection of the storage elastic modulus curve and the loss elastic modulus curve and using the frequency at the intersection and the presence or absence of an inflection point in the loss elastic modulus curve near the intersection as an index is also provided. It was not 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. Using a viscoelasticity measuring device, the storage elastic modulus and loss elastic modulus for each frequency of the external preparation for skin are measured, a storage elastic modulus curve and a loss elastic modulus curve for each frequency are created, and the storage elastic modulus curve And the frequency at the intersection of the loss elastic modulus curve, and using the evaluation method of the external preparation for skin using the frequency at the intersection and the presence or absence of the inflection point of the loss elastic modulus curve in the vicinity of the intersection as an index The inventors have found that such an evaluation can be performed and have completed the invention. That is, the present invention is as follows.
(1) Using a parallel plate viscoelasticity measuring device, the storage elastic modulus (G ′) and loss elastic modulus (G ″) for each frequency of the external preparation for skin are measured, and then the storage elasticity for each frequency Create a modulus curve and a loss modulus curve, determine the frequency at the intersection of the storage modulus curve and the loss modulus curve, and use the frequency at the intersection and the presence or absence of an inflection point in the loss modulus curve near the intersection as an index. The value of G′−G ″ is at least 200 Pa when the frequency is between 100 and 1 rad / s at the angular frequency, and the frequency at the intersection is 0.5 rad / s or less at the angular frequency, and the loss elastic modulus. A method for evaluating an external preparation for skin, characterized in that, when there is an inflection point on a curve, the external preparation for skin is determined to be a highly effective external preparation that provides comfort during use.
(2) The method for evaluating a skin external preparation according to (1), which is a method for evaluating a skin external preparation in the form of a water-in-oil emulsifier .

  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 of external preparation for skin of the evaluation method of the present invention the skin external preparation of the present invention, using a parallel plate type viscoelasticity measuring device, skin Hadagaiyo agent, and the storage modulus for each frequency, loss an elastic modulus were measured, to create a loss modulus curve and storage elastic modulus curves for each frequency, determine the frequency at the intersection of the reservoir modulus curve and loss elastic modulus curve, loss in the vicinity of the frequency and the intersection of the intersection The presence or absence of an inflection point in the elastic modulus curve is used as an index. Using a parallel plate type viscoelasticity measuring device is a common method for viscodynamic measurement, and it is used to measure storage elastic modulus and loss elastic modulus, and to measure the relationship between these two indices. Used to capture the viscodynamic characteristics of an object. Such parallel plate type viscoelasticity measuring device, generally has called rheometer, the commercially resides, the storage modulus by using such commercially available products, the loss modulus It 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 to obtain the change of these values for each frequency , and the X axis is the frequency and the Y axis is the storage elastic modulus (G ′) or loss elastic. Plotting on the coordinates of modulus (G ″), draw 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 the two curves, that is, the frequency at the intersection is small, specifically 0.5 or less, the structure of the skin external preparation is stable and is not easily broken by rubbing, Rubbing can be continued without changing the coefficient of friction, thereby increasing the comfort provided. 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. In addition, the characteristics of these curves, G in between the high-frequency side to the intersection ', G''are both fit to 100~2000Pa, draw a smooth curve. This means that the resistance value is always constant with respect to the stress. Furthermore, the frequency is a value at least 200Pa to G'-G '' between 100~1rad / s at an angular frequency, it is preferable that exists more preferably 300 Pa. 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 an angular frequency of 1 to 10 rad / s, and use this coordinate to create a primary correlation equation Y1.
Step 2: Sample several points on the curve with an angular frequency of 0.01 to 0.1 rad / s, and use these coordinates to create a primary correlation equation Y2.
Step 3: Find the intersection of Y1 and Y2, and use the x coordinate as the frequency of the inflection point.

(2) external skin preparation according to the external preparation for skin present invention according to the present invention, in the above evaluation method, the frequency of the intersection is less 0.5 rad / s angular frequency, for frequencies in the intersection point The frequency of the inflection point of the loss modulus curve exists in the vicinity of within 10% of the frequency at the intersection. 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 water-in-oil emulsifier form of the squeezed form is preferred. Specifically, the polyoxyalkylene-modified form is formed so that the aqueous component is in the form of a water-in-oil emulsifier form in the gel structure formed by the organically modified clay mineral and polyhydric alcohol. Those dispersed with the aid of a surfactant such as methylpolysiloxane are preferred.

1) Organically modified clay mineral The external preparation for skin according to 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 external preparation for skin can be used without 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 according to 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 resulting modified clay mineral, preferably ground to the desired size (preferably particle sizes of 1 to 1000 m), contained in the external skin preparation according to 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 external preparation for skin according to the present invention, this component is preferably contained in an amount of 0.5 to 10% by mass, more preferably 1 to 5% by mass. Such an ingredient works as an emulsifier within the above-mentioned range of contents, 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 applied person 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 break, the internal phase is cross-linked with the organically modified clay mineral, and the emulsion resists the collapse of the emulsified structure. preferable. Preferred examples of such components include N-acyl glutamic acid diesters. The acyl group constituting the component may be saturated or unsaturated, such as 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 skin external preparation which concerns on this invention can be manufactured by adding the arbitrary component for formulation suitably to this component, and processing according to a conventional method. The obtained external preparation for skin is measured for viscodynamic properties according to the evaluation method described above, and it is judged whether or not it is suitable as an external preparation for skin according to 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. Accordingly, the cosmetic 1 has an angular frequency at the intersection of 0.098 rad / s and 0.5 rad / s or less, and a loss elastic modulus curve in the vicinity of 10% of the frequency at the intersection with respect to the frequency at the intersection. An inflection point frequency exists, and a gentle curve is drawn in which 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 angular frequency is 100 to 1 rad / s. The cosmetic 2 cannot calculate the inflection point by simple calculation and does not satisfy this requirement. Accordingly, the cosmetic 1 is discriminated as a cosmetic of the present invention, the cosmetic 2 is discriminated not to belong 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 testing 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 the present invention the cosmetic has an excellent sense of use, it can be seen that allowed to 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 is 0.23, and this cosmetic 3 is also related to the present invention .
It turned out to be a cosmetic. Was evaluated the ones in the same procedures as in Test Example 2 (n = 3), the rate of increase prasterone sulfate is 39.1 ± 8%, the effect of the cosmetic of the present invention was confirmed. 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 (2)

Using a parallel plate type viscoelasticity measuring device, the storage elastic modulus (G ′) and loss elastic modulus (G ″) of each external preparation for skin are measured, and then the storage elastic modulus curve for each frequency Create a loss modulus curve, find the frequency at the intersection of the storage modulus curve and the loss modulus curve, and use the frequency at the intersection and the presence or absence of the inflection point of the loss modulus curve near the intersection as an index,
The value of G′−G ″ is at least 200 Pa when the frequency is between 100 and 1 rad / s at the angular frequency, and the frequency at the intersection is 0.5 rad / s or less at the angular frequency, and the loss modulus curve The skin external preparation evaluation method characterized by determining that it is a skin external preparation with a high effect | action which provides comfort at the time of use when the inflection point of this exists. The method for evaluating a skin external preparation according to claim 1, wherein the method is an evaluation method for a skin external preparation in the form of a water-in-oil emulsifier .

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