JP7797833B2 - Oil-in-water emulsion cosmetics - Google Patents

Description

The present invention relates to an oil-in-water emulsion cosmetic used to moisturize the skin of the face, body, etc.

Emulsion cosmetics that improve the skin's barrier function are used to prevent rough skin, and among these, oil-in-water emulsion cosmetics are preferred because they do not leave an oily film feeling when used.
Because oil-in-water emulsion cosmetics are used in a variety of temperature environments, they require excellent storage stability (hereinafter simply referred to as "stability") in both low- and high-temperature environments. For example, Patent Document 1 discloses a cream composition containing a higher alcohol with an average alkyl chain length of 18 or more, a long-chain acylsulfonate-type anionic surfactant, a polar oil with a molecular weight of 400 or less, and water, and describes that such a cream composition has good stability over a wide temperature range, from high to low, and spreads well on the skin. However, while it is desirable for oil-in-water emulsion cosmetics to have little difference in feel when used in low-temperature and high-temperature environments, a problem has been that spreadability decreases when stored at low temperatures.

To address this issue, Patent Document 2 discloses an oil-in-water emulsion skin cosmetic containing a copolymer of a hydrocarbon oil with an average molecular weight of 800 to 3,000, a higher alcohol with 10 to 24 carbon atoms, a solid oil with a melting point of 30 to 55°C, and 2-methacryloyloxyethyl phosphorylcholine. It describes this skin cosmetic as not having a sticky or squeaky feeling, providing a thick feel upon application, spreading well, and providing an excellent feel when used even at low temperatures.

Another problem with oil-in-water emulsion cosmetics is that they lose their sense of thickness when stored at high temperatures, and there has been a demand for oil-in-water emulsion cosmetics that have an excellent sense of thickness even at high temperatures.
Furthermore, in recent years, there has been an increase in opportunities to disinfect hands with alcohol or the like, and in cases where an oil-in-water emulsion cosmetic is reapplied each time hands are disinfected, frequent disinfection of hands means that oil-in-water emulsion cosmetics are reapplied in multiple layers within a short period of time, and so even in such cases, there has been a demand for no difference in feel before and after reapplication. However, when oil-in-water emulsion cosmetics are reapplied in multiple layers within a short period of time, stickiness or a squeaky feeling can be felt during reapplication, and there has been a demand for an oil-in-water emulsion cosmetic that does not experience any difference in feel when reapplied in multiple layers within a short period of time.

As described above, an oil-in-water emulsion cosmetic that has excellent spreadability at low temperatures and thickness at high temperatures, that does not experience any difference in feel when applied multiple times in a short period of time, and that is highly stable has not yet been developed.

JP 2008-44866 A Japanese Patent Application Laid-Open No. 2020-100607

In view of the above-mentioned current situation, the object of the present invention is to provide an oil-in-water emulsion cosmetic that is highly stable, has excellent spreadability at low temperatures and thickness at high temperatures, and does not cause any difference in feel when applied repeatedly in a short period of time.

As a result of extensive research into solving the above problems, the present inventors discovered that an oil-in-water emulsion cosmetic that exhibits the desired effects can be obtained by selecting specific ingredients and adjusting their blending ratios within specific ranges, and thus completed the present invention.
That is, the present invention provides an oil-in-water emulsion cosmetic containing the following components (A), (B), (C), (D), and (E), and water.
(A) 0.2 to 5% by mass of a monohydric alcohol having an even carbon number of 16 to 22
(B) 0.0005 to 0.1% by mass of a monohydric alcohol having an odd carbon number of 15 to 23
(C) 0.2 to 5% by mass of glyceryl stearate
(D) 0.1 to 4% by mass of polyoxyethylene sorbitan fatty acid ester
(E) 3 to 40 mass% of liquid oil

The oil-in-water emulsion cosmetic of the present invention has the effects of excellent spreadability at low temperatures and thickness at high temperatures, no difference in feel when applied repeatedly in a short period of time, and high stability.
In this specification, "low temperature" refers to 0 to 10°C, "high temperature" refers to 30 to 40°C, and "short time" refers to 10 minutes or less.
Furthermore, "skin" refers to the surface of the body, such as the head including the face, neck, torso, arms, and legs, and is synonymous with the skin.
"Spreadability,""thickness," and "feel in use" are all sensations felt when a sample is applied to the skin and spread over the skin with the fingers or hands, and can be subjectively evaluated by educated and trained panelists (hereinafter simply referred to as "panelers").
"Spreadability" refers to the feel of how easily the sample spreads on the skin. "Thickness" refers to the feel of the thickness of the sample between the finger or hand and the skin. "Feel when using" refers to at least one sensation selected from the group consisting of "sticky feeling" and "creaky feeling.""Stickyfeeling" includes the feeling of residual liquid when the sample remains on the skin and the sticky feeling when the finger or hand sticks to the skin. "Creaky feeling" refers to the feeling of resistance (resistance) that is felt when the sample is spread on the skin.

Hereinafter, an embodiment of the present invention will be described.
The oil-in-water emulsion cosmetic of the present invention contains at least the following components (A), (B), (C), (D), and (E), and water. Each component will be described below.
In this specification, a numerical range defined using the symbol "to" is intended to include both the upper and lower limits of the symbol "to." For example, "2 to 5" represents a range of 2 or more and 5 or less.

<Component (A): Monohydric Alcohol Having an Even Number of Carbon Atoms (16 to 22)>
Component (A) used in the present invention is a monohydric alcohol having an even carbon number of 16 to 22, and is a solid with no fluidity at 25° C. Component (A) is preferably a linear saturated alcohol that has no branched or unsaturated bonds.
Specific examples of component (A) include cetanol, stearyl alcohol, and behenyl alcohol. Behenyl alcohol is particularly preferred from the standpoint of thickness and stability at high temperatures. As component (A), one selected from the above monohydric alcohols can be used alone, or two or more can be used in combination.

The content of component (A) is 0.2 to 5% by mass, preferably 0.4 to 4% by mass, more preferably 0.5 to 3.5% by mass, and particularly preferably 1 to 3% by mass, relative to the total amount of the oil-in-water emulsion cosmetic. If the content of component (A) is too low, the thickness at high temperatures may be insufficient and stability may decrease. If the content of component (A) is too high, the spread at low temperatures may be insufficient, and the feel when applied repeatedly within a short period of time may differ.

<Component (B): Monohydric alcohol having an odd carbon number of 15 to 23 carbon atoms>
Component (B) used in the present invention is a monohydric alcohol having an odd carbon number of 15 to 23, and is a solid that does not have fluidity at 25° C. Component (B) is preferably a linear saturated alcohol that does not have any branched or unsaturated bonds.
Specific examples of component (B) include pentadecanol, heptadecanol, tricosanol, etc. Tricosanol is particularly preferred because it spreads well at low temperatures and does not affect the feel when reapplied. As component (B), one selected from the above monohydric alcohols can be used alone, or two or more can be used in combination.

The content of component (B) is 0.0005 to 0.1% by mass, preferably 0.001 to 0.08% by mass, more preferably 0.005 to 0.05% by mass, and particularly preferably 0.008 to 0.03% by mass, relative to the total amount of the oil-in-water emulsion cosmetic. If the content of component (B) is too low, the spreadability at low temperatures may be insufficient, resulting in differences in the feel when applied multiple times and reduced stability. If the content of component (B) is too high, the effect may not be commensurate with the amount used, which may be economically disadvantageous. In some cases, the spreadability at low temperatures may be insufficient, resulting in differences in the feel when applied multiple times in a short period of time.

The ratio (A)/(B) of the content of component (A) to the content of component (B) is preferably 10 to 5,000, more preferably 15 to 3,000, even more preferably 20 to 1,000, and particularly preferably 25 to 500.

<Component (C): Glyceryl stearate>
Component (C) used in the present invention is glyceryl stearate, which is a monoester of glycerin and stearic acid.
The content of component (C) is 0.2 to 5% by mass, preferably 0.4 to 4% by mass, more preferably 0.5 to 3.5% by mass, and particularly preferably 1 to 3% by mass, relative to the total amount of the oil-in-water emulsion cosmetic. If the content of component (C) is too low, the thickness at high temperatures may be insufficient or stability may decrease, while if the content of component (C) is too high, the elongation at low temperatures may be insufficient.

<Component (D): Polyoxyethylene sorbitan fatty acid ester>
Component (D) used in the present invention is a polyoxyethylene sorbitan fatty acid ester. The fatty acid forming this ester preferably has 12 to 18 carbon atoms and may be either saturated or unsaturated. The number of moles of ethylene oxide added in this ester is preferably 10 to 40, and more preferably 15 to 30.
Examples of component (D) include polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, and polyoxyethylene sorbitan monooleate, and preferred are polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan monooleate. As component (D), one selected from the above esters can be used alone, or two or more can be used in combination.

The content of component (D) is 0.1 to 4% by mass, preferably 0.2 to 3% by mass, more preferably 0.3 to 2.5% by mass, and particularly preferably 0.5 to 2% by mass, relative to the total amount of the oil-in-water emulsion cosmetic. If the content of component (D) is too low, differences in the feel when applied multiple times in a short period of time may occur, and if the content of component (D) is too high, the thickness at high temperatures may be insufficient.

<Component (E): Liquid Oil>
The component (E) used in the present invention is an oil that is liquid at 25°C, i.e., a liquid oil that has fluidity at 25°C, and is typically used in cosmetics, pharmaceuticals, etc., and is selected from the group consisting of polar oils and non-polar oils. Polar oils include triglycerides (vegetable oils) (e.g., olive oil) and ester oils (e.g., cetyl ethylhexanoate). Non-polar oils include hydrocarbon oils (e.g., hydrogenated polyisobutene) and silicone oils (e.g., dimethicone). As component (E), one selected from the above polar oils and non-polar oils can be used alone, or two or more can be used in combination. It is particularly preferred to use one or more polar oils in combination with one or more non-polar oils.

The content of component (E) is 3 to 40% by mass, preferably 4 to 30% by mass, more preferably 5 to 20% by mass, and particularly preferably 8 to 15% by mass, relative to the total amount of the oil-in-water emulsion cosmetic. If the content of component (E) is too low, spreadability at low temperatures may be insufficient, whereas if the content of component (E) is too high, differences in usability may occur when multiple applications are made in a short period of time.
When a polar oil and a non-polar oil are used in combination as component (E), the blending ratio of the polar oil to the non-polar oil (polar oil:non-polar oil) is preferably 10:1 to 1:2, more preferably 8:1 to 1:1, and particularly preferably 6:1 to 2:1.

<Water>
The oil-in-water emulsion cosmetic of the present invention contains water in addition to the above components (A) to (E). As the water, deionized water, ion-exchanged water, or distilled water is preferred.
The content of water is appropriately set so that the total content of the above components (A) to (E) is preferably 75% by mass or more, more preferably 80 to 100% by mass, and particularly preferably 85 to 99% by mass, relative to the total amount of the oil-in-water emulsion cosmetic.

<Other added ingredients>
The oil-in-water emulsion cosmetic of the present invention may further contain, in addition to the above-mentioned components (A) to (E) and water, general components used in cosmetics as additive components.
Examples of other additive components include fatty acids, pH adjusters, antioxidants, sequestering agents, coloring materials, fragrances, pigments, etc. The content of other additive components is preferably 25% by mass or less, and more preferably 20% by mass or less, relative to the total amount of the oil-in-water emulsion cosmetic.

The oil-in-water emulsion cosmetic of the present invention can be produced by known methods. For example, the oil-in-water emulsion cosmetic of the present invention can be produced by mixing an even-numbered saturated fatty alcohol as component (A), an odd-numbered saturated fatty alcohol as component (B), glyceryl stearate as component (C), a polyoxyethylene sorbitan fatty acid ester as component (D), a liquid oil as component (E), and water, heating the mixture to homogeneity, and then stirring and cooling the mixture to near room temperature.

The present invention will be described in more detail below with reference to examples and comparative examples.
<Examples 1 to 13, Comparative Examples 1 and 2>
The oil-in-water emulsion cosmetics shown in Table 1 (Examples 1 to 13) and Table 2 (Comparative Examples 1 and 2) were prepared by known methods and evaluated by the following methods.
In Tables 1 and 2, the numerical values for each component indicate the content (% by mass) relative to the total amount of the emulsion cosmetic. Also, (A)/(B) indicates the content ratio of component (A) to component (B).

The following raw materials were used:
[Component (A)]
Cetanol (1-hexadecanol, a linear saturated alcohol having 16 carbon atoms): special grade reagent (manufactured by Tokyo Chemical Industry Co., Ltd.)
Stearyl alcohol (1-octadecanol, a linear saturated alcohol having 18 carbon atoms): special reagent grade (manufactured by Tokyo Chemical Industry Co., Ltd.)
Behenylic alcohol (1-docosanol, a linear saturated alcohol having 22 carbon atoms): special reagent grade (manufactured by Tokyo Chemical Industry Co., Ltd.)
[Component (B)]
Pentadecanol (1-pentadecanol, a linear saturated alcohol having 15 carbon atoms): special reagent grade (manufactured by Tokyo Chemical Industry Co., Ltd.)
Heptadecanol (1-heptadecanol, a linear saturated alcohol having 17 carbon atoms): special grade reagent (manufactured by Tokyo Chemical Industry Co., Ltd.)
Tricosanol (1-tricosanol, a linear saturated alcohol having 23 carbon atoms): special reagent grade (manufactured by Tokyo Chemical Industry Co., Ltd.)
[Component (C)]
Glyceryl stearate: Monogly MB (NOF Corporation)
[Component (D)]
Polysorbate 60 (polyoxyethylene sorbitan monostearate (saturated fatty acid ester with 20 moles of ethylene oxide added and 18 carbon atoms in the fatty acid)): Nonion ST-60 (manufactured by NOF Corporation)
Polysorbate 80 (polyoxyethylene sorbitan monooleate (unsaturated fatty acid ester with 20 moles of ethylene oxide added and 18 carbon atoms)): Nonion OT-80 (manufactured by NOF Corporation)
[Component (E)]
(polar oil)
Olive oil: refined olive oil (NOF Corporation)
Cetyl ethylhexanoate: Salacos 816 (Nisshin Oillio Group, Ltd.)
(Non-polar oil)
Hydrogenated polyisobutene: Pearleem 6 (manufactured by NOF Corporation)
Dimethicone: KF-96A 20CS (Shin-Etsu Chemical Co., Ltd.)

<Evaluation method>
(1) Evaluation of spreadability at low temperatures Twenty women aged between 25 and 55 served as panelists. After washing their hands with hand soap, they took 0.2 g of an oil-in-water emulsion cosmetic that had been stored at 5°C onto their fingertips and applied it to the back of their hands. The spreadability was evaluated according to the following criteria.
2 points: If you feel that the stretch is very good.
1 point: If you feel that the stretch is somewhat good.
0 points: If you feel that the stretch is poor.

(2) Evaluation of Thickness at High Temperatures Twenty female panelists aged between 25 and 55 washed their hands with hand soap, then took 0.2 g of an oil-in-water emulsion cosmetic that had been stored at 35°C on their fingertips and applied it to the back of their hands. Evaluation was made of the thickness of the cosmetic, based on the following criteria:
2 points: If it feels very thick.
1 point: If you feel it is slightly thick.
0 points: If you feel there is no thickness.

(3) Evaluation of difference in feel when reapplication is performed in a short period of time Twenty female panelists aged 25 to 55 washed their hands with hand soap, and then took 0.2 g of an oil-in-water emulsion cosmetic that had been stored at 25°C on their fingertips and applied it to the back of their hands. After 5 minutes, they took 0.2 g of the oil-in-water emulsion cosmetic that had been stored at 25°C on their fingertips and applied it again to the back of their hands. The difference in feel between the first application and the second application was evaluated according to the following criteria.
2 points: When there is almost no difference in stickiness or squeaky feeling.
1 point: If you feel that there is not much difference in stickiness or squeaky feeling.
0 points: If you feel there is a difference in stickiness or squeaky feeling.

The evaluations of (1) to (3) above were judged according to the following criteria and are shown in Tables 1 and 2. "A" and "B" were judged as passing.
◎: Total score is 35 points or more ○: Total score is 30 points or more but less than 35 points △: Total score is 20 points or more but less than 30 points ×: Total score is less than 20 points

(4) Evaluation of Stability The state of the product after static storage at 5°C and 40°C for one month was checked, and the stability was evaluated as follows.
○: No separation or precipitate was observed.
×: Separation or precipitate was observed.

The oil-in-water emulsion cosmetics of Examples 1 to 13 all had excellent spreadability at low temperatures and a thick feel at high temperatures, and there was no difference in feel when applied multiple times, and they had good stability.
In contrast, in Comparative Examples 1 and 2, sufficient performance was not obtained.
In Comparative Example 1, the content of component (B) was too high, and therefore the elongation at low temperatures was insufficient.
In Comparative Example 2, the component (B) was not contained, and therefore the spread at low temperatures was insufficient, and there was a difference in the feel when the composition was applied repeatedly in a short period of time.

Example 14
Oil-in-water emulsion cosmetics were prepared according to the formulations shown below and evaluated in the same manner as in the above examples.
(A) Cetyl alcohol 1% by mass
(A) Stearyl alcohol 1% by mass
(A) Behenyl alcohol 1% by mass
(B) Pentadecanol 0.01% by mass
(B) Heptadecanol 0.01% by mass
(B) Tricosanol 0.01% by mass
(C) Glyceryl stearate 2% by mass
(D) Polysorbate 60 0.5% by mass
(D) Polysorbate 80 0.5% by mass
(E) Olive oil 2% by mass
(E) Cetyl ethylhexanoate 2% by mass
(E) Hydrogenated polyisobutene 2% by mass
(E) Dimethicone 2% by mass
Water 68% by mass
(Other added ingredients)
Glycerin 6% by mass
Dipropylene glycol 6% by mass
Pentylene glycol 2% by mass
Myristyl myristate 1% by mass
Shea butter 1% by mass
PEG-75 stearate 1% by mass
Carboxyvinyl polymer 0.1% by mass
Alkyl-modified carboxyvinyl polymer 0.1% by mass
Arginine 0.07% by mass
Tocopherol 0.1% by mass
Ethylhexylglycerin 0.1% by mass
Phenoxyethanol 0.3% by mass
Fragrance 0.1% by mass
Polyquaternium-51 0.1% by mass
Total blending amount 100% by mass

The oil-in-water emulsion cosmetic of Example 14 had excellent spreadability at low temperatures and a thick feel at high temperatures, and there was no difference in feel when applied repeatedly within a short period of time, demonstrating good stability.

The oil-in-water emulsion cosmetic of the present invention has water as the continuous phase and can be made into various formulations such as liquid, emulsion, paste, cream, and gel. It can be used as skin care cosmetics such as skin care emulsions and skin care creams; makeup cosmetics such as foundations; and UV protection cosmetics such as sunscreen emulsions.

Claims (1)

An oil-in-water emulsion cosmetic comprising the following components (A), (B), (C), (D), and (E), and water.
(A) 0.2 to 5% by mass of a monohydric alcohol having an even carbon number of 16 to 22
(B) 0.0005 to 0.1% by mass of a monohydric alcohol having an odd carbon number of 15 to 23
(C) 0.2 to 5% by mass of glyceryl stearate
(D) 0.1 to 4% by mass of polyoxyethylene sorbitan fatty acid ester
(E) 3 to 40 mass% of liquid oil