JP7662993B2 - Oil-in-water type skin cleansing cosmetic - Google Patents

Description

The present invention relates to an oil-in-water type skin cleansing cosmetic product.

In recent years, with the growing awareness that excessive cleansing is bad for the skin, it is becoming increasingly recognized that it is important for skin cleansing cosmetics such as hand soaps that remove dirt from the skin not only to cleanse and sanitize the skin, but also to maintain the skin's moisture and prevent rough skin caused by dryness. As a result, skin cleansing cosmetics have been improved not only in terms of cleansing properties, but also in terms of the skin condition after cleansing, such as the moist feeling of the skin after cleansing.

In Patent Document 1, a combination of higher fatty acid salt, N-acylalkyl taurine salt, and O-[2-hydroxy-3-(trimethylammonio)propyl]hydroxyethyl cellulose chloride provides a cream-type skin cleanser that has good foaming, foam volume, foam quality (texture, elasticity), cleaning power, foam cutting, and stability over time, and leaves a moist feeling after rinsing. However, the lack of stickiness after washing is insufficient.

In Patent Document 2, a skin cleanser is provided that is compatible with water, has good foaming properties, and has good foam quality, is not sticky when rinsing, and leaves a moderate moist feeling and no stickiness after washing, by combining a sucrose fatty acid ester composed of a linear saturated fatty acid having 12 to 18 carbon atoms, hydroxypropyl starch phosphate, a 2-methacryloyloxyethyl phosphorylcholine/stearyl methacrylate copolymer, a polyhydric alcohol, a fatty acid soap having 12 to 18 carbon atoms, an anionic surfactant, and an amphoteric surfactant.

JP 2014-181223 A JP 2016-132646 A

In recent years, the importance of keeping the skin clean has been recognized once again, and the frequency of washing has increased. In particular, in the fields of childcare, nursing care, food, and the like, there is a high level of awareness of hygiene, and so the frequency of skin washing is particularly high. Furthermore, there are many stains that are difficult to remove with cold water, and hot water is increasingly being used. For this reason, skin cleansing cosmetics are required not only to have cleansing properties and to leave the skin feeling moist and non-sticky after washing, but also to leave the skin moist after washing, even when repeatedly used with hot water in a short period of time. However, the above compositions left room for improvement, as they did not have sufficient cleansing properties, and did not leave a sufficiently moist feeling after washing when repeatedly used with hot water in a short period of time.

The objective of the present invention is to provide an oil-in-water type skin cleansing cosmetic that has excellent cleansing properties, is non-sticky after cleaning, and leaves a moist feeling after cleaning even when used repeatedly in a short period of time with hot water.

The present invention provides the following.
(1) An oil-in-water type skin cleansing cosmetic preparation, comprising the following component (a) at 0.01 to 10% by mass, component (b) at 10 to 50% by mass, component (c) at 1 to 10% by mass, and component (d) at 1 to 20% by mass:

Component (a): an alkyloxirane derivative represented by formula (1) and satisfying the relationships of the following formulas (2), (3), and (4); Component (b): a polyhydric alcohol having 2 to 6 carbon atoms; Component (c): a polyglycerol fatty acid ester-type nonionic surfactant; Component (d): an oil or fat containing at least an oil or fat that is solid at 25° C.

R ¹ O-(AO) _n -H...(1)

(In formula (1),
R ¹ is a hydrocarbon group having 1 to 6 carbon atoms;
AO is an oxyalkylene group having 3 carbon atoms;
n is the average number of moles of oxyalkylene group AO added, and 50≦n≦150.

0.35≦M _L /M _H ≦0.75 (2)

(In formula (2), the length of the perpendicular line from the maximum point K at which the refractive index intensity on the chromatogram determined by gel permeation chromatography is maximum to the baseline B is defined as L, and of two points on the chromatogram at which the refractive index intensity is L/2, the point with the earlier elution time is defined as point O, and the point with the later elution time is defined as point Q. The intersection point between the straight line G connecting points O and Q and the perpendicular line drawn from the maximum point K to the baseline is defined as P. The distance between point O and the intersection point P is defined as _MH , and the distance between point Q and the intersection point P is defined as _ML .)

A _s = W _1/2 / W _5% ...(3)
0.30≦A _s ≦0.70 (4)

(In formulas (3) and (4), of the two points on the chromatogram where the refractive index intensity is L/20, the one with the earlier elution time is designated as point R, the one with the later elution time is designated as point S, the intersection point of a straight line H connecting points R and S and a perpendicular line drawn from the maximum point K to the baseline B is designated as T, the distance between point R and intersection point T is designated as W _1/2 , and the distance between point R and point S is designated as W _5% .)
(2) The oil-in-water type skin cleansing cosmetic composition according to (1), characterized in that the component (d) further contains an oil that is liquid at 25°C, and the ratio of the mass of the oil that is liquid at 25°C to the mass of the oil that is solid at 25°C (mass of oil that is liquid at 25°C/mass of oil that is solid at 25°C) is 1/8 to 1/2.

The present invention provides an oil-in-water type skin cleansing cosmetic that has excellent cleansing properties, is non-sticky after cleaning, and leaves a moist feeling after cleaning even when used repeatedly in hot water for a short period of time.

FIG. 1 is a model chromatogram diagram for explaining M _L and M _H defined in the present invention. FIG. 2 is a model chromatogram diagram for explaining W _1/2 and W _5% defined in the present invention.

The oil-in-water type skin cleansing cosmetic composition of the present invention contains components (a) to (d). Hereinafter, we will explain the components starting with (a).
(Component (a))
The component (a) is an alkyloxirane derivative represented by formula (1) and satisfying the relationships of formulas (2), (3) and (4).
R ¹ O-(AO) _n -H...(1)

In formula (1), the hydrocarbon group having 1 to 6 carbon atoms represented by R ¹ is a functional group consisting of carbon and hydrogen, and is one selected from an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and is preferably an alkyl group or an alkenyl group.
The carbon number of R ¹ is 6 or less, and more preferably 4 or less. That is, R ¹ is preferably an alkyl group or alkenyl group having 1 to 6 carbon atoms, and most preferably an alkyl group having 1 to 6 carbon atoms. R ¹ may be a linear hydrocarbon group or a branched hydrocarbon group, but is preferably a linear hydrocarbon group. Examples of linear alkyl groups having 1 to 6 carbon atoms include methyl groups, ethyl groups, propyl groups, butyl groups, and hexyl groups. The hydrocarbon groups having 1 to 6 carbon atoms represented by R ¹ may be of one type or two or more types.

In formula (1), AO is an oxyalkylene group having 3 carbon atoms, specifically an oxytrimethylene group or an oxymethylethylene group, with an oxymethylethylene group being preferred.
In formula (1), n is the average number of moles of oxyalkylene group AO added, and is 50 or more. If n is less than 50, the viscosity is low and the non-stickiness after washing may be lacking. However, as n increases, the stickiness after washing increases, so n is preferably 150 or less, and more preferably 120 or less.

The component (a) further satisfies the following formula (2):
0.35≦M _L /M _H ≦0.75 (2)
(In formula (2), the length of the perpendicular line from the maximum point K on the chromatogram where the refractive index intensity is maximum to the baseline B is defined as L, and of two points on the chromatogram where the refractive index intensity is L/2, the one having the earlier elution time is defined as point O, and the one having the later elution time is defined as point Q. The intersection point between the straight line G connecting the points O and Q and the perpendicular line drawn from the maximum point K to the baseline is defined as P. The distance between the point O and the intersection point P is defined as _MH , and the distance between the point Q and the intersection point P is defined as _ML .)

That is, the alkyloxirane derivative used in the present invention is specified by a chromatogram obtained by gel permeation chromatography (GPC) using a differential refractometer. This chromatogram is a graph showing the relationship between refractive index intensity and elution time. Here, FIG. 1 is a model diagram of a chromatogram obtained by gel permeation chromatography of an alkyloxirane derivative, with the horizontal axis showing elution time and the vertical axis showing refractive index intensity obtained using a differential refractometer. When a sample solution is injected into a gel permeation chromatograph and developed, elution begins with the molecule with the highest molecular weight, and the elution curve rises as the refractive index intensity increases. Thereafter, after passing the maximum point K where the refractive index intensity is at its maximum, the elution curve begins to decline.

M _L /M _H are each calculated from the chromatogram as follows.
(1) Draw a perpendicular line from the maximum point K of the refractive index intensity on the chromatogram to the baseline B, and let the length of the perpendicular line be L.
(2) Of the two points on the chromatogram where the refractive index intensity is L/2, the one with the earlier elution time is designated as point O, and the one with the later elution time is designated as point Q.
(3) Let P be the intersection point between a straight line G connecting points O and Q and a perpendicular line drawn from the maximum point K of the refractive index intensity to the baseline B.
(4) Let the distance between point O and intersection point P be M _H , and the distance between point P and point Q be M _L .

In addition, in the gel permeation chromatography of the alkyloxirane derivative of the present invention, if there are multiple maximum points of refractive index intensity in the chromatogram, the point with the highest refractive index intensity among them is taken as maximum point K. Furthermore, if there are multiple maximum points of the same refractive index intensity, the one with the later elution time is taken as maximum point K. In this case, peaks due to the developing solvent used in the gel permeation chromatography and false peaks due to baseline fluctuations caused by the column or device used are excluded.

Here, component (a) satisfies _ML / _MH of 0.35≦ _ML / _MH ≦0.75. If _{ML/MH is greater than 0.75, the viscosity of the alkyloxirane derivative decreases, and when this is incorporated into an oil-in-water type skin cleansing cosmetic, the moist feeling after repeated washing with hot water is impaired. From this viewpoint, ML / MH} is set to 0.75 or less, preferably 0.65 or less, and more preferably 0.55 or less. In addition, the smaller _ML / _MH is, the greater the bias toward the high molecular weight side in _the molecular weight distribution, and the higher the viscosity of the alkyloxirane derivative is. That is, if _ML / _MH is smaller than 0.35, the viscosity becomes too high, which causes the skin to lose its non-stickiness after washing. For this reason, M _L /M _H is set to 0.35 or more, and from the viewpoint of moist feeling after repeated washing with hot water, it is more preferable to set it to 0.40 or more, and particularly preferable to set it to 0.45 or more.

In addition, the alkyloxirane derivative used in the present invention has a chromatogram, which is represented by the refractive index intensity and elution time obtained by gel permeation chromatography using a differential refractometer, that is asymmetric on the left and right, and the asymmetry value As of the peak of the chromatogram, which is calculated as shown below, satisfies formulas (3) and (4).
As=W _1/2 /W _5% ...(3)
0.30≦As≦0.70 (4)

The calculation method of As will be further explained with reference to the model diagram of a chromatogram in Figure 2. The horizontal axis indicates elution time, and the vertical axis indicates refractive index intensity obtained using a differential refractometer.
(1) Draw a perpendicular line from the maximum refractive index intensity point K on the chromatogram to the baseline B, and let the length of the line be L.
(2) Of the two points on the chromatogram where the refractive index intensity is L/20, the one with the earlier elution time is designated as point R, and the one with the later elution time is designated as point S.
(3) Let T be the intersection point between a straight line H connecting points R and S and a perpendicular line drawn from the maximum point K of the refractive index intensity to the baseline B.
(4) The distance between point R and intersection point T is W _1/2 , and the distance between point R and point S is W _5% .

In the present invention, As satisfies 0.30≦As≦0.70. By setting As to 0.70 or less, the viscosity is appropriately improved, and a moist feeling can be imparted after repeated washing with hot water. From this viewpoint, it is more preferable that As is 0.65 or less. Furthermore, the smaller As is, the greater the bias toward the high molecular weight side in the molecular weight distribution, which leads to an increase in viscosity, etc. Therefore, from the viewpoint of imparting non-stickiness after washing, As is set to 0.30 or more, and more preferably 0.57 or more.

In the present invention, gel permeation chromatography (GPC) for determining M _L , M _H and As is carried out by using a SHODEX (registered trademark) GPC101 GPC dedicated system as the system, a SHODEX RI-71s differential refractometer, a SHODEX KF-G guard column and three SHODEX KF804L columns in series, with the column temperature at 40° C. and tetrahydrofuran as the developing solvent flowing at a flow rate of 1 ml/min, injecting 0.1 ml of a 0.1 wt % tetrahydrofuran solution of the obtained reaction product, and using a BORWIN GPC calculation program to obtain a chromatogram represented by refractive index intensity and elution time.

Specific examples of the alkyloxirane derivative include polypropylene glycol methyl ether, polypropylene glycol ethyl ether, polypropylene glycol propyl ether, polypropylene glycol butyl ether, polypropylene glycol pentyl ether, and polypropylene glycol hexyl ether, and preferably polypropylene glycol propyl ether and polypropylene glycol butyl ether.

Hereinafter, the total mass of the oil-in-water type skin cleansing cosmetic composition is taken as 100% by mass.
If the content of the (a) component is high, not only will stickiness occur after washing, but washing properties may also decrease, so the content of the (a) component is set to 10% by mass or less, preferably 7% by mass or less, more preferably 3% by mass or less, and particularly preferably 2% by mass or less. Also, if the (a) component is low, not only will the lack of stickiness after washing be impaired, but the moist feeling after washing when repeatedly used in hot water in a short period of time may also be difficult to feel, so the content of the (a) component is set to 0.01% by mass or more, preferably 0.1% by mass or more, and more preferably 0.5% by mass or more.

(Component (b))
The (b) component is a polyhydric alcohol having 2 to 6 carbon atoms. Examples of the polyhydric alcohol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, methylpropylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,2-pentylene glycol, 1,2-hexylene glycol, 1,6-hexanediol, glycerin, trimethylolpropane, diglycerin, glucose, maltose, and sorbitol. These (b) components may be used alone or in appropriate combination of two or more. Among these, glycerin, dipropylene glycol, and pentylene glycol are preferred, and glycerin and dipropylene glycol are more preferred.

When the total mass of the oil-in-water type skin cleansing cosmetic is taken as 100% by mass, a high content of component (b) may cause stickiness after cleansing, so the content of component (b) is set to 50% by mass or less, preferably 40% by mass or less, and more preferably 30% by mass or less. Also, if the content of component (b) is low, it may be difficult to feel a moist feeling after cleansing when repeatedly used with hot water in a short period of time, so the content is set to 10% by mass or more, preferably 15% by mass or more, and more preferably 25% by mass or more.

(Component (c))
Component (c) is a polyglycerol fatty acid ester type nonionic surfactant.

The polyglycerol fatty acid ester type nonionic surfactant is an ester of polyglycerol having an average degree of polymerization of 2 to 10 and a fatty acid having 10 to 22 carbon atoms.
The average degree of polymerization of this polyglycerol is preferably 2 to 8, more preferably 2 to 6, further preferably 2 or 3, and particularly preferably 2.

The fatty acid is preferably a fatty acid having 12 to 20 carbon atoms, more preferably a fatty acid having 16 to 18 carbon atoms. These fatty acids may be saturated, unsaturated, straight-chained, or branched, and may also be a mixture of these fatty acids. Examples of fatty acids include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, isostearic acid, oleic acid, and coconut oil fatty acid. Among these, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, and oleic acid are preferred, palmitic acid, stearic acid, and isostearic acid are more preferred, and palmitic acid and isostearic acid are even more preferred, with isostearic acid being particularly preferred.

The HLB of the component (c) is preferably from 2 to 10. The HLB is calculated by the following formula.
HLB=20(1-S/A)
S: saponification value of ester, A: acid value of fatty acid

When the total mass of the oil-in-water type skin cleansing cosmetic is taken as 100% by mass, a small amount of component (c) not only reduces the cleansing ability but may also make it difficult to feel the lack of stickiness after rinsing, so the content of component (c) is set to 1% by mass or more, preferably 2% by mass or more, and more preferably 3% by mass or more. Also, a large amount of component (c) may make it difficult to feel the moist feeling after washing when repeatedly used in hot water for a short period of time, so the content of component (c) is set to 10% by mass or less, preferably 8% by mass or less, and more preferably 7% by mass or less.

((d) Component: oil and fat)
The component (d) used in the present invention is a fat or oil, and contains at least a fat or oil that is solid at 25°C.
Specific examples of fats and oils include camellia oil, olive oil, avocado oil, meadowfoam oil, macadamia nut oil, coconut oil, sunflower oil, sesame oil, grapeseed oil, rice oil, rapeseed oil, glyceryl triisostearate, glyceryl triisopalmitate, glyceryl tri-2-ethylhexanoate, glyceryl tri(capryl-caprate), triethylhexanoin, etc. Examples of fats and oils that are solid at 25° C. include coconut butter, shea butter, cacao butter, hydrogenated palm oil, hydrogenated rapeseed oil, etc.

As fats and oils that are liquid at 25°C, olive oil, sunflower oil, sesame oil, grapeseed oil, and rapeseed oil are preferred, and as fats and oils that are solid at 25°C, shea butter and cacao butter are preferred. Particularly preferably, as component (d), fats and oils that are liquid at 25°C and fats and oils that are solid at 25°C can be used in combination. In this case, the mass ratio (fat and oil that is liquid at 25°C)/(fat and oil that is solid at 25°C) is preferably 1/10 to 10/1, more preferably 1/8 to 1/2, and even more preferably 1/6 to 1/3. As a combination of fats and oils that are liquid at 25°C and fats and oils that are solid at 25°C, for example, a combination of sunflower oil and shea butter is particularly preferred.

If the content of component (d) is low, it may be difficult to feel a moist feeling after washing when repeatedly used in hot water for a short period of time, so the content of component (d) is set to 1% by mass or more, preferably 3% by mass or more, and more preferably 5% by mass or more. Also, if the content of component (d) is high, not only may the non-stickiness after washing be impaired, but the cleansing properties may also be reduced, so the content of component (d) is set to 20% by mass or less, preferably 15% by mass or less, and more preferably 10% by mass or less.

The oil-in-water type skin cleansing cosmetic composition may contain additives other than the components (a) to (d). As such additives, those used in cosmetic applications may be used, such as moisturizers, thickeners, preservatives, pH adjusters, and fragrances.
When the total mass of the oil-in-water type skin cleansing cosmetic is taken as 100% by mass, the total amount of additives is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less.
The remainder of the oil-in-water type skin cleansing cosmetic other than the components (a) to (d) and any additive components is water. The water content is preferably 20 to 90% by mass, more preferably 30 to 85% by mass, and even more preferably 40 to 80% by mass.

The present invention will be described in more detail below with reference to examples and comparative examples. Compounds a-1 to a-3 used in the examples and comparative examples were synthesized as follows.

(Reference synthesis example: synthesis of composite metal cyanide complex catalyst)
Into 2.0 ml of an aqueous solution containing 2.1 g of zinc chloride, 15 ml of an aqueous solution containing 0.84 g of potassium hexacyanocobaltate K ₃ Co(CN) ₆ was dropped over 15 minutes while stirring at 40°C. After the dropwise addition, 16 ml of water and 16 g of tert-butyl alcohol were added, the temperature was raised to 70°C, and stirring was continued for 1 hour. After cooling to room temperature, a filtration operation (first filtration) was performed to obtain a solid. To this solid, 14 ml of water and 8.0 g of tert-butyl alcohol were added, and the mixture was stirred for 30 minutes, followed by a filtration operation (second filtration) to obtain a solid.
Furthermore, 18.6 g of tert-butyl alcohol and 1.2 g of methanol were added to this solid again, and after stirring for 30 minutes, a filtration operation (third filtration) was performed. The obtained solid was dried at 40°C under reduced pressure for 3 hours to obtain 0.7 g of a composite metal cyanide complex catalyst.

(Compounds a-1 to a-3)
A stainless steel 5-liter (capacity 4,890 ml) pressure-resistant reactor equipped with a thermometer, pressure gauge, safety valve, nitrogen gas inlet tube, stirrer, vacuum exhaust tube, cooling coil, and steam jacket was charged with 200 g of butyl propylene glycol and 0.2 g of the composite metal cyanide complex catalyst of the reference synthesis example. After nitrogen replacement, the temperature was raised to 110° C., and 210 g of methyl oxirane was charged from the nitrogen gas inlet tube over 4 hours under conditions of 0.3 MPa or less. At this time, the pressure and temperature changes over time in the reaction vessel were measured. After 4 hours, the pressure in the reaction vessel suddenly decreased. Thereafter, while maintaining the reaction vessel at 110° C., methyl oxirane was gradually charged from the nitrogen gas inlet tube under conditions of 0.6 MPa or less, and 3,287 g of methyl oxirane was continuously added under pressure with stirring. At this time, the time required for adding 840 g of methyloxirane was 60 minutes, the time required for adding 2,100 g was 108 minutes, and the time required for adding 3,287 g was 132 minutes. After the addition was completed, the mixture was reacted at 110° C. for 1 hour, and then 1,680 g was extracted from the reaction vessel.
The temperature of the residue in the reaction vessel was then raised to 110° C., and 174 g of methyloxirane was added over 20 minutes from the nitrogen gas inlet tube under conditions of 0.6 MPa or less while maintaining the temperature inside the reaction vessel at 110° C. After completion of the addition, the reaction was carried out at 110° C. for 1 hour, and then 619 g was again extracted from the reaction vessel, and while blowing in nitrogen gas, the reaction vessel was subjected to reduced pressure treatment at 75 to 85° C. and 50 to 100 Torr for 1 hour, followed by filtration.

The M _L , M _H and As of the resulting reaction product (compound a-1) were determined using a Showa Denko GPC (gel permeation chromatography) measuring device as described above. As a result, M _L /M _H was 0.52 and As was 0.61.

The temperature of the residue in the reaction vessel was further increased to 110°C, and while maintaining the temperature inside the reaction vessel at 110°C, 121 g of methyloxirane was added over 30 minutes from the nitrogen gas inlet tube under conditions of 0.6 MPa or less. After completion of the addition, the reaction was carried out at 110°C for 1 hour, and then 370 g was again withdrawn from the reaction vessel, and while blowing in nitrogen gas, the reaction vessel was subjected to reduced pressure treatment at 75-85°C and 50-100 Torr for 1 hour, followed by filtration. The resulting reaction product (compound a-2) was measured by gel permeation chromatography.
The M _L /M _H of the resulting reaction product (compound a-2) was 0.42 and As was 0.59.

The temperature of the residue in the reaction vessel was further increased to 110°C, and while maintaining the temperature inside the reaction vessel at 110°C, 122 g of methyloxirane was added over 30 minutes from the nitrogen gas inlet tube under conditions of 0.6 MPa or less. After reacting at 110°C for 1 hour, the mixture was reduced in pressure at 75-85°C and 50-100 Torr for 1 hour while blowing in nitrogen gas, and then filtered. The resulting reaction product (compound a-3) was measured by gel permeation chromatography.
The M _L /M _H of the resulting reaction product (compound a-3) was 0.36 and As was 0.57.

Moreover, for compound a' (PREMINOL S1004F), the chromatogram does not have one refractive index maximum point, and is not a unimodal peak, so the values of M _L /M _H and As at the peak having the largest refractive index maximum point are shown.
In Table 1, the hydroxyl value was measured in accordance with JIS K-1557-1, the kinematic viscosity was measured in accordance with JIS K-2283, the degree of unsaturation was measured in accordance with JIS K-1557, and the molecular weight was calculated from the hydroxyl value.

[Examples 1 to 14, Comparative Examples 1 to 6]
Oil-in-water type skin cleansing cosmetics were prepared by the following method with the blending ratios shown in Tables 2 to 4. The common additive components in Tables 2 to 4 are the 10 components shown in Table 5.
That is, an aqueous phase containing component (b) and ion-exchanged water was mixed with an oily component consisting of components (a), (c), (d) and common additive components 1, 2 and 3, heated to 75 to 80°C and mixed using a homomixer, and then common additive components 4 and 5 were added, cooled and common additive components 6, 7, 8, 9 and 10 were added to obtain an oil-in-water type skin cleansing cosmetic.
The oil-in-water type skin cleansing cosmetic compositions thus obtained were evaluated in four categories according to the following evaluation criteria. The evaluation results are shown in Tables 2 to 4.

[Evaluation items and evaluation criteria]
The following items were evaluated, and the total score was used to rank the items on a four-level scale from "A" to "B".
(1) Cleansing Ability Twenty men and women (aged 24 to 54) were used as panelists. 5 g of rapeseed oil was applied to the hands as an oily stain, and 2 g of the oil-in-water type skin cleansing cosmetic was rubbed into the hands five times. The hands were then rinsed with running water without scrubbing, and the degree of removal of the stain was judged as follows. The total score of the 20 panelists was calculated and the judgment was made.

2 points: If you feel that the dirt has been removed.
1 point: If you feel that the stain is difficult to remove.
0 points: If you feel that the dirt has not been removed.

A score of 30 or more in total was judged to be an oil-in-water type skin cleanser with excellent cleansing properties.

(2) Non-stickiness after cleansing Twenty men and women (aged 24 to 54) were used as panelists. They applied 2 g of the oil-in-water type skin cleansing cosmetic to their hands five times, rinsed them under running water without rubbing, and towel-dried their hands. After five minutes, they judged the non-stickiness as follows, and the total score of the 20 panelists was calculated and the judgment was made.

2 points: If there is no stickiness.
1 point: If it feels slightly sticky.
0 point: If sticky feeling is felt.

A score of 30 or more was judged to be an oil-in-water type skin cleanser with excellent non-stickiness.

(3) Moist feeling after repeated washing with hot water Twenty men and women (aged 24 to 54) were used as panelists. After applying 2 g of the oil-in-water type skin cleansing cosmetic to their hands five times, they rinsed with hot water (approximately 38°C) and towel-dried their hands. This procedure was repeated 10 times over a period of approximately five minutes. The moist feeling five minutes after towel-drying was evaluated as follows, and the total score of the 20 panelists was calculated and evaluated.

2 points: If you feel it is moist.
1 point: If you feel it is slightly moist.
0 point: If you feel there is no moisturizing sensation.

A score of 30 or more was judged to be an oil-in-water type skin cleanser that provided an excellent moist feeling after repeated washing with hot water.

<4-level evaluation based on total score>
◎: Total score is 35 or more. ○: Total score is 30 or more but less than 35. △: Total score is 20 or more but less than 30. ×: Total score is less than 20.

From Examples 1 to 14, it was found that all of the oil-in-water type skin cleansing cosmetics using the components of the present invention had good cleansing properties, were non-sticky after cleansing, and left the skin feeling moisturized after repeated cleansing with hot water.

On the other hand, in Comparative Examples 1 to 6, sufficient performance was not obtained.
In Comparative Example 1, since the component (a) was not contained, the lack of stickiness after washing and the moist feeling after repeated washing with hot water were insufficient.
In Comparative Example 2, component (a) was not contained, and an alkyloxirane derivative with a narrow molecular weight distribution was blended as component (a'), and the lack of stickiness after washing and the moist feeling after repeated washing with hot water were insufficient.
In Comparative Example 3, since component (b) was not contained, the moist feeling after repeated washing with hot water was insufficient.
In Comparative Example 4, since the component (c) was not contained, the cleaning properties and non-stickiness after cleaning were insufficient.
Comparative Example 5 did not contain component (d) and contained polyoxyethylene alkyl ether as component (d'), and the cleaning properties, lack of stickiness after washing, and moist feeling after repeated washing with hot water were insufficient.
In Comparative Example 6, since the component (d) was not contained, the moist feeling after washing and the moist feeling after repeated washing with hot water were insufficient.

Claims (2)

The oil-in-water type skin cleansing cosmetic preparation comprises the following components: 0.01 to 10 mass % of component (a), 10 to 50 mass % of component (b), 1 to 10 mass % of component (c), and 1 to 20 mass % of component (d):

Component (a): an alkyloxirane derivative represented by formula (1) and satisfying the relationships of the following formulas (2), (3), and (4); Component (b): a polyhydric alcohol having 2 to 6 carbon atoms; Component (c): a polyglycerol fatty acid ester-type nonionic surfactant; Component (d): an oil or fat containing at least an oil or fat that is solid at 25° C.

R ¹ O-(AO) _n -H...(1)

(In formula (1),
R ¹ is a hydrocarbon group having 1 to 6 carbon atoms;
AO is an oxyalkylene group having 3 carbon atoms;
n is the average number of moles of oxyalkylene group AO added, and 50≦n≦150.

0.35≦M _L /M _H ≦0.75 (2)

(In formula (2), the length of the perpendicular line from the maximum point K at which the refractive index intensity on the chromatogram determined by gel permeation chromatography is maximum to the baseline B is defined as L, and of two points on the chromatogram at which the refractive index intensity is L/2, the point with the earlier elution time is defined as point O, and the point with the later elution time is defined as point Q. The intersection point between the straight line G connecting points O and Q and the perpendicular line drawn from the maximum point K to the baseline is defined as P. The distance between point O and the intersection point P is defined as _MH , and the distance between point Q and the intersection point P is defined as _ML .)

A _s = W _1/2 / W _5% ...(3)
0.30≦A _s ≦0.70 (4)

(In formulas (3) and (4), of the two points on the chromatogram where the refractive index intensity is L/20, the one with the earlier elution time is designated as point R, the one with the later elution time is designated as point S, the intersection point of a straight line H connecting points R and S and a perpendicular line drawn from the maximum point K to the baseline B is designated as T, the distance between point R and intersection point T is designated as W _1/2 , and the distance between point R and point S is designated as W _5% .)
2. The oil-in-water type skin cleansing cosmetic composition according to claim 1, wherein component (d) further comprises an oil that is liquid at 25°C, and the ratio of the mass of the oil that is liquid at 25°C to the mass of the oil that is solid at 25°C (mass of oil that is liquid at 25°C/mass of oil that is solid at 25°C) is 1/8 to 1/2.

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