JP2003083873A - Evaluation method of usability of bar-like cosmetic material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and reliable evaluation method for usability of a bar-like cosmetic material such as lip rouge. SOLUTION: This evaluation method of usability of bar-like cosmetic material comprises putting the bar-like cosmetic material 1 cut in rounds in a prescribed thickness between two flat plates 2A and 2B; crushing it by applying up to a force of 60-250N in the axial direction; measuring, with respect to the bar-like cosmetic material in the crushed state, the distortion dependency of dynamic viscoelasticity at a prescribed temperature by use of a parallel plate (distortion range: 0.1-300%); and evaluating the dynamic touch felt by the lip or hand in the application of the cosmetic material 1 from the storage elasticity G' (Pa) or tanδ in a distortion of a prescribed value within 0.01-1%, or the magnitude of the distortion (%) where tanδ is a prescribed value within the range of 0.5-1.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the feeling of use during or after application of a stick-shaped cosmetic such as lipstick. In the evaluation method of the present invention, the strain dependence of the dynamic viscoelasticity of the stick-shaped cosmetic is measured, and the magnitude relationship between the storage elastic modulus and the value of tan δ obtained by the measurement is used as an index of the feeling of use of the stick-shaped cosmetic. And

[0002]

2. Description of the Related Art Evaluation of the feeling of use of lipsticks is generally accomplished by a development engineer (a development engineer who has more than 5 years of experience in lipstick development). The sensory evaluation by is mainly. Familiar development engineers routinely evaluate various prescriptions and are very familiar with this type of evaluation. However, it is inefficient in development to evaluate the feeling of use of lipstick every time by sensory evaluation, and it cannot be objectively quantified or generalized (accumulation of experience of individual evaluation results belongs to the evaluator). For),
Alternatively, there is a problem that it is not possible to evaluate materials whose safety has not been confirmed.

Therefore, there is a demand for an objective evaluation method that does not rely on sensory evaluation. As such an evaluation method, it has been attempted to use the dynamic friction force and the coating amount obtained from the measurement of the resistance force using a stylus. In this method, a lipstick is attached to a surface property measuring device (HEIDON-14 type manufactured by Shinto Kagaku Co., Ltd.), a load corresponding to the coating stress (0.49 to 1.96N) is applied, and a speed corresponding to the coating speed ( Two
000 to 4000 mm / min), and the dynamic friction coefficient and the coating amount are measured.

[0004] However, this method can evaluate "goodness of spread" and "goodness of spread (application amount)", which are some of the feel items when applying the cosmetic stick, but "smoothness of spreadability". It could not be used as an evaluation index for complex feelings such as or "creaminess". On the other hand, there have been attempts to grasp the feel of fluid cosmetics when using them from thixotropy (for example, Matsumoto et al., F.
ragrance Journal, 1990-8, p
46), there was no report on the correspondence with the application feeling evaluation of solid cosmetics such as lipstick.

Therefore, an object of the present invention is to provide a simple, safe and highly reliable evaluation method for the feeling of use of a stick-shaped cosmetic such as lipstick.

[0006]

According to the present invention, a stick-shaped cosmetic material that is sliced into a predetermined thickness is sandwiched between two flat plates and crushed by applying a maximum force of 60 to 250 N in the axial direction, Then, with respect to the crushed bar-shaped cosmetic, the strain dependence of dynamic viscoelasticity at a predetermined temperature was measured using a parallel plate (strain range: 0.01 to 300%), and the strain was 0.01. Storage modulus G ′ (Pa) or tan δ or tan δ at a predetermined value within the range of 1% is 0.5 to
The feeling of use of the stick-shaped cosmetic composition for evaluating the mechanical feel felt by the lips or hands during application of the stick-shaped cosmetic composition from the magnitude of the value of the strain (%) that is a predetermined value within the range of 1.5 The above-mentioned object is achieved by providing the evaluation method (1) (hereinafter, this evaluation method is referred to as the first evaluation method). The "axial direction" refers to the long direction of the stick when the stick-shaped cosmetic material is regarded as an anisotropic stick, and refers to the direction shown by the arrow in Fig. 1 described later. The above-mentioned "slice" means that a slice is cut by a plane substantially perpendicular to the axial direction.

Further, according to the present invention, a stick-shaped cosmetic material, which is sliced into a predetermined thickness, is sandwiched between two flat plates, and the axial direction is 150-150.
A force of 250 N is applied to crush the product, and then the flat cosmetic is slid to knead the cosmetic product in a crushed condition under the condition of applying a force of 65 to 150 N to the cosmetic product.
With respect to the rod-shaped cosmetic material in a kneaded state, the strain dependence of dynamic viscoelasticity at a predetermined temperature was measured using a parallel plate (strain range: 0.01 to 300%), and a tan δ value at a predetermined strain value was measured. And tan before and after the distortion value
A method for evaluating the feeling of use of a stick-shaped cosmetic is provided by comparing the δ value and evaluating the mechanical feel felt by the lips or hands during application of the stick-shaped cosmetic, or the sensation felt by the lips after application, based on their size. By doing so, the above object is achieved (hereinafter, this evaluation method is referred to as the second evaluation method).

Further, according to the present invention, in the manufacturing process of a stick-shaped cosmetic material, the manufactured product is subjected to the first or second evaluation method to judge whether or not the product has a desired usability. If, however, it is determined that the desired feeling of use cannot be obtained, a method for producing a stick-shaped cosmetic product is provided, in which the blending formulation of predetermined components is increased or decreased, or a feedback operation such as change of production process conditions is performed. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on its preferred embodiments. First, the first evaluation method will be described by taking a lipstick, which is a typical stick-shaped cosmetic material, as an example. The lipstick evaluation item evaluated in the first evaluation method is the mechanical feel felt by the lips or hands during application of the lipstick. Such feelings include (1) lightness of spread during application of lipstick, (2) smoothness of spread, (3)
Typical examples are good adhesion, (4) soft touch, and (5) creamyness.

The lightness of spread refers to the sensation that the lipstick slips lightly on the lips. Smoothness is the sensation that lipstick does not get caught on the lips. Good stickiness means that a lot of lipstick sticks to the lips with a single operation. The soft touch means that the lips are soft to the touch. Creamy is the feeling that lipstick grows softly on your lips as it grows.

In order to evaluate the mechanical feel of the lip or the hand when applying the lipstick, the strain dependence of the dynamic viscoelasticity of the lipstick is measured, and the storage elastic modulus (Pa), ta obtained by the measurement is measured.
The value of the strain (%) at which nδ or tanδ becomes a predetermined value is used. As described above, there have been attempts to evaluate the feeling of use of the lipstick from the measurement of the dynamic viscoelasticity of the lipstick.
The major feature of this evaluation method is that the lipstick is pretreated by a specific method prior to the measurement. This pretreatment means, as shown in FIG. 1, a lipstick 1 sliced into a predetermined thickness is sandwiched between two flat plates 2A and 2B, and the axial direction of the lipstick (indicated by an arrow P in FIG. 1). In addition, it is an operation of crushing by applying a force of 60 to 250 N at maximum. The present inventors have found that the pretreatment makes it possible to quantify the feeling of use of the lipstick. The reason for this is not always clear, but the card house structure in lipsticks mainly composed of wax and oil components (a general structure of lipsticks, where wax crystals grown in the form of scales are different from each other in the scale-like crystal face portion and edge. The three-dimensional solid structure with many voids is formed so that the parts collide with each other, and the structure in which oil is included in the voids) is destroyed by the crushing operation described above, and that state is actually the lip. It is thought that this is because it is similar to the state in which lipstick is applied to.

The thickness T for slicing the lipstick is not critical to the evaluation method of the present invention, and may be a thickness that facilitates measurement depending on the thickness of the lipstick, and is generally 1.5 to 7 mm, especially 2 to
It is about 5 mm. The maximum force for crushing the sliced lipstick is 60-250N, especially 100-2
It is preferably 30 N because good reproducibility results can be obtained. The flat plates 2A and 2B are made of glass,
Plastic, metal, etc. can be used. The areas of the flat plates 2A and 2B are sufficiently larger than the cross-sectional area of the lipstick. As the pressurizing means, for example, a press machine or a weight can be used, but it may be pressed by hand while monitoring the force applied by a balance or the like. It is preferable that the time required for crushing the lipstick is 0.1 to 10 seconds, particularly 0.3 to 1 second, because good reproducibility results can be obtained. The environment at the time of crushing is not critical to the evaluation method of the present invention, as long as lipstick is used,
Generally, a normal environment such as a temperature of 10 to 25 ° C. and a humidity of 40 to 70% RH can be used.

The lipstick thus crushed must be immediately subjected to the dynamic viscoelasticity measurement described below.
If the crushed lipstick is left unattended, the oil component will ooze out and the distribution of the wax and oil component will change,
This is not preferable because the reproducibility of measurement deteriorates.

The strain dependence of the dynamic viscoelasticity of the crushed and pretreated lipstick is then measured. The measurement of dynamic viscoelasticity requires a rheometer of the type capable of controlling the strain applied to the sample during measurement with good reproducibility in a short time. Rheometrics Fl for this purpose
A uid Spectrometer (RFS II) is preferably used. However, it is not particularly limited to this model as long as it is a rheometer capable of controlling the strain in a short time with good reproducibility. A parallel plate or a cone plate (cone-flat plate) can be used as the fixture for mounting the measurement sample, but the present invention is used for the purpose of facilitating the measurement operation and enabling all evaluations with one lipstick. In, the measurement is performed using a parallel plate. As the parallel plate, it is preferable to use one having a diameter of 10 to 50 mm, particularly 17 to 26 mm from the viewpoint that one lipstick can perform all measurements. The distance between the parallel plates at the time of measurement is 0.2 to 0.8 mm, especially 0.
It is preferable to sandwich the pretreated lipstick between the parallel plates so as to have a thickness of 3 to 0.5 mm from the viewpoint that one lipstick can perform all measurements. The environment for measuring the dynamic viscoelasticity is preferably a temperature of 20 to 40 ° C., particularly 28 to 33 ° C., from the viewpoint that the temperature can be measured at a temperature close to the temperature of the lip on which lipstick is actually applied. Humidity is not critical to the evaluation method of the present invention, and can be set in a normal environment, for example, 45 to 70% RH.

The measurement of dynamic viscoelasticity has a strain range of 0.0.
1 to 1000%, especially 0.01 to 300%, is sufficient for lipstick evaluation. For the same reason, the applied frequency can be 0.1 to 5 Hz. FIG. 2 shows the strain dependence of the storage elastic modulus and tan δ thus measured. The measurement conditions are a temperature of 30 ° C. and an applied frequency of 0.16 Hz.

With respect to the storage elastic modulus and tan δ, the respective values within a predetermined range of strain and the tactile scores numerically expressing the mechanical feel felt by the lips or hands when the lipstick was applied by sensory evaluation by a skilled developer. It has been found that there is a correlation with the value of. Here, the "feeling score" is one in which five experienced development engineers evaluate the feel of the lipstick and rank the feel of each lipstick into five levels (hereinafter, "skilled development engineer's score"). Or abbreviated as "development engineer's score"),
The higher the rank value, the better the feeling. More specifically, the strain is 0.01 to 1%, preferably 0.
It was found that the storage elastic modulus and tan δ within the range of 08 to 0.3% and the results of sensory evaluation correlate well. This range is a range in which the strain is relatively small, and is considered to be a state that reflects the structure of only the crushed lipstick. As an example of this, FIG. 3 shows the relationship between the storage elastic modulus (Pa) at a strain of 0.1% and the smoothness of spread by sensory evaluation (a score of a well-developed engineer). Further, FIG. 4 shows the relationship between tan δ at a strain of 0.1% and smoothness of spread by sensory evaluation (a score of a well-developed engineer). In both FIGS. 3 and 4, the measurement conditions are a temperature of 30 ° C. and an applied frequency of 0.16 Hz. As is clear from FIG. 3, there is a negative correlation between the storage elastic modulus and the smoothness of spread, and it can be seen that the smaller the value of the storage elastic modulus, the better the smoothness. It is considered that the value of the storage elastic modulus is an index of the softness of the lipstick obtained by crushing the lipstick card house structure immediately after the structure is destroyed. Also, as is clear from FIG.
There is a positive correlation between nδ and the smoothness of spread, and ta
It can be seen that the larger the value of nδ, the better the smoothness. The magnitude of the tan δ value is considered to be an index of the flowability of the lipstick in the state immediately after the destruction of the lipstick card house structure obtained by crushing. As described above, the mechanical feel felt by the lips or the hand during application of lipstick can be evaluated from the magnitude of the storage elastic modulus or the value of tan δ.

Further investigations by the present inventors based on the measurement results and the like shown in FIG. 2 show that the tan δ value has a predetermined value and that the lips or hands during sensory evaluation of the lipstick are sensory evaluated by the development engineer. It has also been found that there is a correlation with the felt mechanical feel. Specifically, the value of tan δ is a predetermined value within a range of 0.5 to 1.5, preferably a predetermined value within a range of 0.7 to 1.3, and more preferably 1 (elasticity). It was found that the value of the strain at which the contribution becomes equal to the viscous contribution) correlates well with the result of the sensory evaluation. tan δ
This range is considered to correspond to a state where the viscous and elastic contributions to the lipstick deformation and flow are about the same in the lipstick application operation. As an example of this,
FIG. 5 shows the relationship between the strain (%) at tan δ = 1 and the creamy by sensory evaluation. The measurement conditions in FIG. 5 are a temperature of 30 ° C. and an applied frequency of 0.16 Hz, and the horizontal axis indicates that the larger the value, the better the creaminess. As is clear from FIG. 5, there is a negative correlation between the strain and the creamy, and it is understood that the smaller the strain value, the better the creamy. t
The strain at which an δ becomes 1 represents the strain amount that changes from the state immediately after the destruction of the lipstick card house structure obtained by crushing to the state where the viscous and elastic contributions to the lipstick deformation and flow are equal. , It is considered that the creaminess is related to the flow in which the viscous contribution and the elastic contribution are equal. In this way, from the magnitude of the strain value, it is possible to evaluate the mechanical feel of the lips or hands when applying the lipstick.

3 and 4 illustrate the correlation between the storage modulus or tan δ and the smoothness of spread, respectively, and FIG. 5 illustrates the correlation between the strain and creamy. However, according to the study by the present inventors, as is clear from Examples described later, the storage elastic modulus, tan δ, or strain is other than smoothness and creamyness of spread, the lip or lip when applying lipstick. It has been found to correlate with the mechanical feel of the hand. In particular, the storage elastic modulus has a high correlation with the lightness of the spread and the softness of the touch in addition to the smoothness of the spread described above, and the tan δ has the lightness of the spread as well as the smoothness of the spread described above. There is a high correlation with the softness of touch and creaminess, and with respect to distortion, there is a high correlation with the lightness of spread, smoothness of spread, good adhesion, and softness of touch in addition to the creaminess described above.

As is clear from the above description, the storage elastic modulus, tan δ, or the strain at which tan δ has a predetermined value can be used alone for evaluating the mechanical feel of the lips or hands when applying lipstick. However, at least two of these three factors are used, at least two of them are selected as explanatory variables, and multiple regression analysis is performed with the score of sensory evaluation as the objective variable, and the storage elastic modulus is based on the analysis result. , Tan δ
It was found that there is a case where the quality of each feel can be quantified more quantitatively by creating a calculation formula for predicting the feel from at least two of the strains at which tan δ has a predetermined value and using it for the evaluation of the feel. did. In particular, storage modulus, tan δ
From the viewpoint of improving reliability, it is preferable to select three factors, ie, distortion and distortion, as explanatory variables, and to perform multiple regression analysis using sensory evaluation scores as objective variables. The multiple regression analysis is a well-known regression analysis method in statistics, and need not be described in detail in this specification. In the present invention, the storage elastic modulus, t
For the strains at which an δ and tan δ have predetermined values, a relatively well-correlated calculation formula was obtained when the logarithmic value (common logarithmic value) was used. For example, storage modulus (G '),
If tan δ (t) and the distortion (S) at which tan δ has a predetermined value are used as explanatory variables, and Z is a score of sensory evaluation that is an objective variable, Z = αlog as a regression equation.
(G ′) + βlog (t) + γlog (S) + C may be created and the coefficients α, β and γ and the constant C may be obtained.

Further, in the present evaluation method, in addition to the evaluation method described above, the strain dependence of dynamic viscoelasticity of pretreated lipstick is measured to obtain a tan δ-strain curve, and whether the curve has a peak or a shoulder. In other words, it was found that the correlation with the mechanical feel felt by the lips or the hand when applying the lipstick can be evaluated more reliably. Specifically, the distortion value is 1%
When the tan δ value has a peak and / or a shoulder at any position near and near 100%, or the strain value is 1
A peak or shoulder near 0% correlates well with the mechanical feel felt by the lips or hands when applying lipstick. In particular, when the tan δ value has a peak and / or a shoulder at any of the strain values near 1% and 100%, it correlates well with the lightness of lipstick spread, and the strain value approaches 10%. When it has a peak or a shoulder, it correlates well with a moist feeling.

Next, the second evaluation method will be described by taking a lipstick as an example similarly to the first evaluation method. Regarding the second evaluation method, only the points different from the first evaluation method will be described, and for the points that are not particularly described, the description regarding the first evaluation method will be applied as appropriate. The lipstick evaluation item evaluated in the second evaluation method is the mechanical feel felt by the lips or hands during application of the lipstick, as in the first evaluation method.
In addition to this, in the second evaluation method, the mechanical feel felt by the lips after application of lipstick can also be evaluated. A typical example of the mechanical feel felt by the lips after application of the lipstick is the moist feeling of the lipstick after application. The reason why the moist feeling is the mechanical feel that the lips feel after applying the lipstick is that when the upper and lower lips are rubbed together after applying the lipstick, the shearing force between the lipsticks applied to the upper and lower lips, respectively. Is due to the action of. The moist feeling of lipstick after application refers to the feeling that a protective film is on the lips.

In order to evaluate the mechanical feel felt by the lips or hands at the time of applying the lipstick or after the application by the second evaluation method, the strain dependence of the dynamic viscoelasticity of the lipstick is measured and measured. The tan δ-strain curve relationship obtained by Similar to the first evaluation method, the present evaluation method is characterized in that the lipstick is pretreated by a specific method prior to the measurement of the dynamic viscoelasticity. This pretreatment is the following 2
Including one operation. First, similarly to the first evaluation method, the lipstick sliced into a predetermined thickness is sandwiched between two flat plates and crushed by applying a predetermined pressure in the axial direction of the lipstick. Next, the flat plate is slid to knead the lipstick while applying a predetermined pressure to the crushed lipstick. The present inventors have found that by measuring the tan δ-strain curve of the lipstick subjected to such a pretreatment, it becomes possible to quantify the feel score of the lipstick. The reason for this is not always clear, but the destruction of the lipstick cardhouse structure by crushing
It is considered that this is because the kneading operation further progresses, and the destruction process / the condition after the destruction is similar to the application process / the condition after application of the lipstick.

The pretreatment of this evaluation method will be described in more detail. The crushing operation of the lipstick is the same as the first evaluation method except that the crushing force is 150 to 250N. Regarding the kneading operation subsequent to the crushing operation, the lipstick has an average of 65 to 150 N, preferably 95 to
As shown in FIG. 6, the flat plate 2 under the condition that a force of 140 N is applied.
Slide A and 2B horizontally. Good reproducibility results can be obtained by applying a force within this range. The sliding speed is 0.5 to 30 mm / in relative speed between the flat plates 2A and 2B.
Seconds, particularly 1 to 15 mm / second are preferable because good reproducibility results can be obtained. The environment of kneading by sliding can be the same as the environment of crushing. It is preferable that the sliding distance is 10 to 30 mm, particularly 15 to 21 mm, and the number of sliding times is 1 to 20 reciprocations, particularly 1 to 15 reciprocations, since good reproducibility results can be obtained.

Then, the strain dependence of the dynamic viscoelasticity of the crushed and kneaded pretreated lipstick is measured. The measuring device, conditions, and environment can be the same as in the first evaluation method. A curve (t-S curve) between the value t of tan δ and the value S of strain is drawn from the measurement result, and the tan δ value at a predetermined strain and tan δ at values before and after the strain value.
The inventors of the present invention found that by comparing the values with the values, the mechanical feeling felt by the lips or hands during application of the rod-shaped cosmetic or the sensation felt by the lips after application of the bar-shaped cosmetics can be evaluated. Specifically, the value t of tan δ when the distortion is a certain value S
And the values before and after the distortion value S (S-ΔS and S + ΔS)
When compared with the tan δ values (t ₋ and t ₊ ) at
The t-S curve has a peak when t is greater than both t _- and t ₊ . Also, if t is greater than the average value of t ₋ and t ₊ , the t-S curve has a shoulder.
Furthermore, if t is smaller than either t _{− or} t ₊ , t ₋
The S curve has a bottom. Then, it has been found that the mechanical feel felt by the lips or hands during application of the lipstick or the sensation felt by the lips after application can be evaluated depending on which strain value position the t-S curve has the peak, shoulder, and bottom. Furthermore, it was also found that when there is a peak or a shoulder, the tan δ value at the top of the peak can evaluate the mechanical feel felt by the lips or hands during the application of lipstick or the sensation felt by the lips after application. Incidentally, the value of ΔS is in the range of 0.1 to 1.5, particularly 0.3 to 0.8 when expressed by the common logarithmic value of the strain S in the evaluation of lightness of spread described later. It is preferable because good reproducibility can be obtained, and the evaluation of moist feeling is 0.5 to 2.0, particularly 0.8.
The range of -1.2 is preferable.

For example, as shown in FIG. 7, in the t-S curve, when the tan δ value has a peak and / or a shoulder at both the strain values near 1% and 100%, lipstick It was found to correlate with a lighter spread (ie, the mechanical feel of the lips or hands when applying lipstick). The strain value is 1%, that is, the destruction of the card house structure begins immediately after the lipstick is applied to the lips, and further destruction of the structure progresses as the application operation progresses (100% strain state). The card house structure is easily broken by the coating operation (in other words, the spread is light).

Further, as shown in FIG. 8, in the t-S curve, when the tan δ value has a peak at a position where the strain value is around 10%, a moist feeling after application of the lipstick (that is, lipstick after application of lipstick). It has been found that there is a correlation with the (mechanical feel) felt by. Since the tan δ value has a peak at this position, it is considered to reflect the strength of the cohesive force in the cohesive structure of the lipstick formed by the coating operation (load of strain of less than 10%). Furthermore, when there is a peak or shoulder of the tan δ value at a position where the strain value is near 10%, the height of the peak or shoulder with respect to the baseline and the moist feeling after application of the lipstick (that is, the mechanics felt by the lip after application of the lipstick). It was also found that there is a correlation with

The evaluation method of the present invention can be used, for example, in the development of new stick-shaped cosmetics, quality control in the manufacturing process of products, demonstration of products in stores, and the like. When the evaluation method of the present invention is used for quality control of a product, for example, the product is randomly extracted in the manufacturing process of the product and subjected to the evaluation method of the present invention to determine whether or not the product has a desired feel. to decide. When it is determined that the desired feeling of use cannot be obtained, a feedback operation such as increasing or decreasing the formulation of predetermined components necessary or effective for obtaining the feel and changing manufacturing process conditions is performed. As a result, it is possible to manufacture a product with no variation in usability.

The object to be measured by the evaluation method of the present invention is not limited to the above-mentioned lipstick, but any cosmetic having a stick-like shape such as lip balm, stick-shaped foundation or eye color may be used.
There is no particular limitation on the type.

Example 1 Commercially available lipsticks shown in Table 1 below were sliced into 3 mm-thick slices, sandwiched between two glass plates, and subjected to a force of 30 ° C. and a humidity of 55% RH. It was crushed for 0.6 seconds so that the maximum was 200N. Immediately press the crushed lipstick into two parallel plates (diameter 2
5 mm) and sandwiched between the parallel plates in the dynamic viscoelasticity measuring device. At this time, the distance between the parallel plates was set to 0.45 mm. 0.16Hz
Was applied to measure the strain dependence of dynamic viscoelasticity. The measurement environment was a temperature of 30 ° C. and a humidity of 55% RH.
From the obtained measurement results, storage elastic modulus (Pa) at a strain of 0.1%, tan δ at a strain of 0.1%, and tan δ =
The strain (%) at 1 was determined. The results are shown in Table 1.

Separately from this, five development engineers (1) lightness of spread of the lipsticks shown in Table 1,
Sensory evaluations of (2) smoothness of spread, (3) goodness with stickiness, (4) softness of touch, and (5) creamyness were performed on a scale of 1 to 5. Further, the average value of the sensory scores of the five items (1) to (5) (which can be considered as the overall score of the feeling of use) was determined. The results are shown in Table 1. The numerical value means that the higher the value, the higher the evaluation.

Next, of the above-mentioned sensory evaluation items, (5)
The following multiple regression analysis was performed for creaminess and the average value of 5 items. Using the storage elastic modulus (G ′), tan δ (t) and strain (S) values obtained from the measurement results of dynamic viscoelasticity, and the score (Z) of each sensory evaluation, the form of the formula is Z
= Αlog (G ') + βlog (t) + γlog (S)
Multiple regression analysis was performed to obtain + C, and the coefficients α, β and γ and the constant C were obtained. Further, the correlation coefficient R was obtained. The results are shown in Table 2.

Obtained coefficients α, β and γ and a constant C
By applying the value of to the above equation, G ', t, S
From this value, a multiple regression equation for calculating an expected value (theoretical value) for each feel can be obtained. Then, the values of G ', t, and S of each lipstick were substituted into the obtained multiple regression equation, and the creamy and the theoretical value of 5 item averages were calculated. The results are shown in Table 1. Furthermore,
The theoretical value of each sensory evaluation thus obtained and the actual measurement value (the score of the development engineer) were plotted on a graph, and the degree of correlation between them was observed. The results are shown in FIGS. 9 and 10.

[0033]

[Table 1]

[0034]

[Table 2]

As is apparent from the results shown in Tables 1 and 2 and FIGS. 9 and 10, the theoretical value (the calculated value by the multiple regression equation) of the sensory evaluation calculated by the evaluation method of the present invention and the actually measured value (development) There is a significant correlation between the creaminess and the average value of 5 items. Next, in order to verify the reliability of the obtained multiple regression equation, using this multiple regression equation, a lipstick different from the one used for the calculation of the multiple regression equation (commercial lipstick 15 manufactured by Company B) was tested. ', T, S were measured, and each was 1.35 x 1
0 ⁵ Pa, became 0.531,0.22%. By applying this to the multiple regression equation, the theoretical value of creaminess was 3.87, and the theoretical value of the five-item average was 4.02. On the other hand, as a result of sensory evaluation by the development engineer, the theoretical value of creamy 4, 5 item averages was 4.0, and the predicted value by the multiple regression equation and the evaluation of the development engineer were almost the same.
In addition, as shown in the lower part of Table 1, the prediction values by the multiple regression equation and the evaluation by the development engineer for two other types of lipsticks were almost the same. From this, it was found that multiple regression analysis is usefully used in the method of the present invention.

Separately from this, a tan δ-strain curve was obtained from the measurement results of dynamic viscoelasticity. In lipstick, which was highly evaluated for its lightness in sensory evaluation, the strain was around 1% and around 100%. A tan δ value peak and / or shoulder was observed in each. From these results, in the tan δ-strain curve, tan δ value peaks and /
Alternatively, it was found that there is a correlation between the presence of the shoulder and the favorable lightness of the spread.

Example 2 Commercial lipstick 4 (lipstick manufactured by Company B)
Were crushed in the same manner as in Example 1, and further 12 on average.
The glass plate was slid and kneaded under a state where a force of 0 N was applied. The sliding speed is 20 mm, which is the relative speed between the flat plates 2A and 2B.
/ Sec, the sliding distance was 18 mm, and the sliding frequency was 2 reciprocations.
After that, the strain dependence of dynamic viscoelasticity was measured in the same manner as in Example 1. When a tan δ-strain curve was obtained from the measurement results, the strain was found to be around 1% and 100%, respectively.
A peak of tan δ value was recognized.

Separately from this, the lightness of spreadability of this lipstick was subjected to a sensory evaluation, and a 5-point scale of 1 to 5 gave a score of 5, indicating that the spreadability was good.

From these results, in the tan δ-strain curve, the strain is near 1% and 100%, respectively.
It was found that there is a correlation between the tan δ value peak being observed and the lightness of spreading being good.

[Example 3] Commercial lipstick 7 (lipstick manufactured by Company D)
Using, the same pretreatment as in Example 2 (crushing and kneading)
Then, the strain dependence of dynamic viscoelasticity was measured. When the tan δ-strain curve was obtained from the measurement results, the strain was 1
A peak of tan δ value was recognized at around 0%.

Separately, a moisturizing feeling of this lipstick was sensory-evaluated to be 5 points in a 5-point scale of 1 to 5, and it was found that the moisturizing feeling was good.

From these results, it was found that in the tan δ-strain curve, a peak of tan δ value was observed in the vicinity of strain of 10%, and a good moist feeling was correlated.

[0043]

According to the evaluation method of the present invention, the feeling of use of stick-shaped cosmetics such as lipsticks can be evaluated with high reliability.
Moreover, in the evaluation method of the present invention, both the pretreatment of the measurement object and the dynamic viscoelasticity measurement are simple, and therefore the evaluation can be easily performed. Further, the evaluation method of the present invention is also well suited for the purpose of evaluating the feel of a compounded formulation of a material such as a novel substance whose safety has not been confirmed.

[Brief description of drawings]

FIG. 1 is a schematic view showing a state in which a lipstick to be measured is crushed.

FIG. 2 is a graph showing strain dependence of storage elastic modulus and tan δ.

FIG. 3 is a graph showing the relationship between the storage elastic modulus (Pa) at a strain of 0.1% and the smoothness of spread by sensory evaluation.

FIG. 4 is a graph showing a relationship between tan δ at a strain of 0.1% and smoothness of spread by sensory evaluation.

FIG. 5 is a graph showing the relationship between the strain (%) when tan δ = 1 and the creamy by sensory evaluation.

FIG. 6 is a schematic diagram showing a state in which the lipstick after crushing is kneaded by sliding.

FIG. 7 is a graph showing the relationship between tan δ and strain.

FIG. 8 is a graph showing the relationship between tan δ and strain.

FIG. 9 is a graph showing a relationship between a theoretical value and a measured value of sensory evaluation.

FIG. 10 is a graph showing a relationship between a theoretical value and a measured value of sensory evaluation.

[Explanation of symbols]

1 lipstick 2A, 2B flat plate

Continued front page    (72) Inventor Momoko Shimizu             2-1-3 Culture, Sumida-ku, Tokyo Kao Stock Association             Company research institute (72) Inventor Kensuke Yoshida             2-1-3 Culture, Sumida-ku, Tokyo Kao Stock Association             Company research institute

Claims (7)

[Claims] 1. A stick-shaped cosmetic material, which is sliced into a predetermined thickness, is sandwiched between two flat plates and, in the axial direction, a maximum of 60 to 250.
Strain dependence of dynamic viscoelasticity at a predetermined temperature was measured using a parallel plate for the stick-shaped cosmetic material in a crushed state by applying a force of N, and then the strain was 0.0
Storage elastic modulus G ′ at a predetermined value within the range of 1 to 1%
(Pa) or tan δ or tan δ is 0.5 to 1.
Evaluation of the feeling of use of the stick-shaped cosmetic, which evaluates the mechanical feel felt by the lips or hands during application of the stick-shaped cosmetic, based on the magnitude of the strain (%) value that is a predetermined value within the range of 5 Method. 2. An analysis result of multiple regression analysis in which at least two of the storage elastic modulus, the tan δ, and the strain are used, and at least two of these values are selected as explanatory variables, and sensory evaluation scores are used as objective variables. The method for evaluating the feeling of use of a sticky cosmetic according to claim 1, wherein a calculation formula for predicting a feeling is created from at least two of the storage elastic modulus, the tan δ and the strain based on the above, and used as an index of the feeling. 3. A stick-shaped cosmetic material, which is cut into a predetermined thickness and sandwiched between two flat plates, is crushed by applying a force of 150 to 250 N in the axial direction, and then crushed. The flat cosmetic is kneaded by sliding the flat plate under the condition that a force of 65 to 150 N is applied, and then, the parallel cosmetic is used for the stick cosmetic in a kneaded state at a predetermined temperature. The strain dependence of dynamic viscoelasticity is measured, and the tan δ value at a predetermined strain value and the tan δ values at values before and after the strain value are compared. A method for evaluating the feeling of use of a stick-shaped cosmetic material, which evaluates the mechanical feeling felt by the user or felt by the lips after application. 4. Whether or not the tan δ value has a peak and / or a shoulder at a position where the strain value is near 1% and 100%, and if there is a peak or a shoulder, the tan δ value at the peak is large or small, 4. The method for evaluating the feeling of use of a stick-shaped cosmetic composition according to claim 3, wherein the mechanical feel felt by the lips or hands during application of the stick-shaped cosmetic composition is evaluated. 5. Whether or not the tan δ value has a peak at a position where the strain value is around 10%, and if there is a peak or shoulder, it is the height of the peak or shoulder with respect to the baseline. The method for evaluating the feeling of use of a stick-shaped cosmetic composition according to claim 3, wherein the mechanical feel of the lips is evaluated. 6. The parallel plates having a diameter of 10 to 50 mm are used, and the distance between the parallel plates is 0.3 to.
The rod shape according to claim 1 or 3, wherein the strain dependence of dynamic viscoelasticity is measured by sandwiching the rod-shaped cosmetic material in a crushed state or a kneaded state so as to be 0.5 mm. How to evaluate the feeling of use of cosmetics. 7. In the process of manufacturing a stick-shaped cosmetic material, the manufactured product is subjected to the evaluation method according to claim 1 or 3,
When it is judged whether or not the product has the desired feeling of use, and when it is judged that the desired feeling of use cannot be obtained, the formulation of the prescribed ingredients is increased or decreased, or the manufacturing process conditions are changed. A method for manufacturing a stick-shaped cosmetic material which performs a feedback operation.