JP7626382B2 - A beauty method to brighten the entire face using microneedling - Google Patents

Description

The present invention provides a new cosmetic method that improves blood circulation throughout the face and brightens the skin tone.

In terms of beauty, not only daily care such as the use of lotions and cosmetics suited to the subject's skin condition and massage, but also the use of iontophoresis and lasers, beauty technology continues to evolve day by day. In recent years, "microneedle technology" has been attracting attention in the beauty industry. In the beauty industry, microneedle technology is a technology that makes it possible to provide deeper moisture to the skin by solidifying biodegradable ingredients such as hyaluronic acid into needle-like shapes and attaching them to the skin, allowing the ingredients to dissolve. It is a skin care item developed with the aim of penetrating hyaluronic acid and other ingredients into the skin, rather than simply applying them to the surface of the skin. By applying it to the skin for a few hours, for example overnight, the beauty effects obtained by microneedles are recognized to not only increase moisture, but also to increase skin firmness and elasticity, and improve dark circles and dullness under the eyes.

Aging, stress, and other factors can cause the face to become congested and darker in color. Brightening or maintaining a bright facial tone is an important factor in maintaining a youthful appearance. To achieve this, daily efforts are required, such as improving blood circulation in the skin and activating metabolism. Therefore, the beauty industry is looking for a simple way to improve blood circulation in the face and brighten the overall facial tone.

Patent No. 3553956

The objective of the present invention is to provide a new cosmetic method that improves blood circulation throughout the face and brightens the overall facial tone.

The inventors discovered that continuous use of microneedles under the eyes not only improves the tone of dark circles under the eyes, but also, surprisingly, improves blood circulation throughout the face, brightening the overall facial tone, leading to the completion of the present invention. It was not known that microneedles have such an effect. Therefore, the present application provides the following invention.

(1) A beauty method for brightening the overall facial tone by attaching a microneedle sheet containing multiple microneedles to part of the face.
(2) A beauty method as described in (1), in which a microneedle sheet is applied to the areas under the eyes where dark circles appear.
(3) A cosmetic method according to (1) or (2), wherein the microneedles are made of hyaluronic acid.
(4) Any of the cosmetic methods (1) to (3), wherein the height of the microneedles is 50 to 200 μm.
(5) Any of the cosmetic methods (1) to (4), wherein the area of the microneedle sheet is 500 to 3,000 ^mm2 .
(6) A microneedle sheet formulation that contains multiple microneedles made of hyaluronic acid and improves blood circulation when applied to a part of the face.
(7) A microneedle sheet formulation of (6) that brightens the overall facial tone.
(8) A microneedle sheet formulation of (6) or (7) to be applied to the area under the eyes.
(9) The microneedle sheet preparation according to any one of (6) to (8), wherein the height of the microneedles is 50 to 200 μm.
(10) The microneedle sheet preparation according to any one of (6) to (9), having an area of 500 to 3,000 ^mm2 .

By applying the microneedle sheet of the present invention to a part of the face and using it continuously for a certain period of time, it is possible to improve blood circulation not only in the part where the sheet is applied, but also in the entire face, brightening the overall facial tone.

This shows that application of a microneedle sheet improves blood circulation not only at the application site but also in the surrounding area.

In the present invention, the microneedle sheet refers to a microneedle array in which multiple fine microneedles are formed on the surface of a substrate.

The cosmetic method of the present invention is carried out by applying a microneedle sheet to a part of the face, preferably an area where dark circles under the eyes are formed, for several hours, for example overnight, preferably 1 to 12 hours, for example 3 to 10 hours, for example 1 to 4 times a week, preferably twice a week, for example for 1 to 6 months, preferably for 2 months. This method of continuous application may be carried out continuously, or may be carried out intermittently, for example, at intervals of several months, several times a year.

According to the cosmetic method using the microneedle sheet of the present invention, by applying the sheet to a part of the face and using it continuously, blood circulation is improved not only in the part where the sheet is applied, but also over a wide area of the face, and as a result, the facial tone that has become dull and dark due to congestion can be brightened. The degree of facial tone can be determined, for example, by tracking changes in the L value and a value using a spectrophotometric colorimetric system. The L value is an index of skin transparency, and an increase in this value means that the transparency of the skin has been improved, and thus the skin appears brighter. The a value is an index of skin redness, and a decrease in this value means that the redness has been improved, and thus the skin becomes whiter. Facial blood circulation can be determined by laser Doppler testing, tracking laser imaging speckles, and the like.

The material forming the microneedle used in the present invention is not particularly limited as long as it has a certain degree of hardness so that it can be inserted into the skin and cause stimulation. However, since it is to be attached to the skin for a long time, it needs to be a biocompatible material, and is preferably formed from a material that can dissolve or swell in the body. Examples of such materials include polysaccharides such as hyaluronic acid, chitosan, maltose, alginate, amylose, and agarose, celluloses such as carboxymethyl cellulose and hydroxypropyl cellulose, and starch, and may be formed from each material alone or from a mixture of two or more materials appropriately blended. A particularly preferred material is hyaluronic acid. Hyaluronic acid is usually used in the form of a salt, and examples of the salt include metal salts such as sodium salt and potassium salt. Hyaluronic acid can be used from low molecular weight hyaluronic acid with an average molecular weight of 10,000 or less as measured by HPLC, to high molecular weight hyaluronic acid with an average molecular weight of 800,000 or more, and low molecular weight and high molecular weight hyaluronic acid can be mixed appropriately. Alternatively, the material forming the microneedle may be formed from a resin that does not dissolve or swell in the body and does not affect the body, and examples of the material include, but are not limited to, polymethyl methacrylate, cellulose acetate, ethyl cellulose, polyethylene resin, polypropylene resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinylidene chloride resin, vinyl acetate-vinyl chloride copolymer, polyamide resin, polyester resin, ABS resin, SIS resin, SEBS resin, urethane resin, silicone resin, aluminum, etc.

The substrate of the microneedle sheet may be made of the same or different material as the microneedles, as long as the microneedles can be formed on its surface, and is not particularly limited. Examples of the material include films or sheets of polymethyl methacrylate, cellulose acetate, ethyl cellulose, polyethylene resin, polypropylene resin, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, vinyl chloride resin, vinylidene chloride resin, vinyl acetate-vinyl chloride copolymer, polyamide resin, polyester resin, ABS resin, SIS resin, SEBS resin, urethane resin, silicone resin, aluminum, etc. Alternatively, the substrate may be a film or sheet made of collagen and/or gelatin.

The microneedles may contain medicinal ingredients such as water-soluble drugs and cosmetic ingredients that have been conventionally used as transdermal absorption preparations, for example, whitening ingredients such as ascorbyl palmitate, kojic acid, rucinol, tranexamic acid, potassium 4-methoxysalicylate, pyrimidinylpyrazole compounds, liquorice extract, oil-based licorice extract, and vitamin A derivatives; anti-wrinkle ingredients such as retinol, retinoic acid, retinol acetate, and retinol palmitate; blood circulation promoting ingredients such as tocopherol acetate, capsaicin, and vanillylamide norylate; diet ingredients such as raspberry ketone, evening primrose extract, and seaweed extract; antibacterial ingredients such as isopropyl methylphenol, photosensitizers, and zinc oxide; and vitamins such as vitamin D2, vitamin D3, and vitamin K.

The shape of the microneedle is not particularly limited, but a cone shape, a truncated cone shape, or a cone-shaped shape is preferable so that it can be easily inserted into the skin and does not cause pain when inserted. Note that a cone-shaped shape is a so-called volcano shape, in which the side of the truncated cone is curved inward.

If the diameter of the base of the microneedle is too thin, it will break easily when inserted into the skin, and if it is too thick, it will cause pain when inserted into the skin, so an appropriate diameter is 0.15 to 1.0 mm, preferably 0.15 to 0.5 mm. If the tip diameter is too thin (sharp), it will break easily when inserted into the skin, and if it is too thick, it will be difficult to insert into the skin and will cause pain, so an appropriate diameter is 0.01 to 0.2 mm.

The height of the microneedles must be high enough to penetrate the skin and cause stimulation, but if they are too high there is a risk that they may reach the skin basement membrane and may be prone to breaking when being penetrated into the skin, so a height of 50 μm to 1000 μm, preferably 100 to 500 μm, is appropriate. In addition, if the microneedles and the pitch of the microneedles are too short, they will be difficult to penetrate into the skin, and if they are too long, the number of microneedles per area will be small, and the effect of the present invention may not be achieved, so a height of 0.3 to 1.0 mm is appropriate.

In the present invention, since the microneedle sheet is applied to a part of the face to improve blood circulation and brighten the face, it is preferable that the area of the microneedle sheet has a certain degree of size. Although not particularly limited, the area is preferably at least 200 ^mm2 , and more preferably 500 to 3,000 ^mm2 .

The method for producing the microneedle array of the present invention is not particularly limited, and any conventionally known method may be used, for example, the following production method.
(1) A method in which an aqueous solution of a material mainly composed of a microneedle-forming material such as hyaluronic acid, to which medicinal ingredients or cosmetic ingredients may be added as necessary, is cast onto a mold punched in the shape of a microneedle, and the material is dried at room temperature or by heating to evaporate the water, and a substrate is laminated thereon and then peeled off to transfer the microneedle onto the substrate.

(2) A method in which the aqueous solution is cast onto the surface of the mold to form a layer, and then the layer is dried at room temperature or by heating to evaporate the water, and then peeled off. With this method, a microneedle array is obtained in which both the substrate and the microneedles are made of a material mainly composed of a microneedle-forming material, to which medicinal ingredients or cosmetic ingredients may be added as necessary.

(3) A method in which an aqueous solution of a material mainly made of microneedle-forming material, to which medicinal or cosmetic ingredients may be added as necessary, is injection molded onto a substrate into the shape of a microneedle, and then the water is evaporated and the material is dried at room temperature or by heating.

Experiment 1
Thirty-one healthy women aged 30 to 55 with dark circles under their eyes were asked to apply the microneedle sheet twice a week during sleep for four weeks to the dark circles under both eyes (the so-called pigmented areas). The specifications of the microneedle sheet used are as follows:
Material: Sodium hyaluronate (average molecular weight 50,000 to 100,000) Mixing area: approx. 975 ^mm2
Needle height: 200μm
Number of needles: 2000
Base diameter: 200μm
Needle pitch: 540μm

After 4 weeks, the subjects' facial color was measured using a spectrophotometer (Konica Minolta: Model CM-600d). The results are shown in the table below.

In the table above, the L value represents the transparency of the skin, the a value represents the redness of the skin, and the b value represents the yellowness of the skin. The higher the L value, the better the results, while the lower the a and b values.
As is clear from the table above, continued use of the microneedle sheet not only improved redness (a value) at the pigmented area where the sheet was applied, but also improved redness (a value) on the cheek where the sheet was not directly applied.

Experiment 2
Furthermore, the blood flow condition of the face of the subject was measured using a laser Doppler (model name: OMEGAFLO-N1, OMEGA WAVE Co., Ltd.). The results are shown in the table below.

As is clear from the table above, continued use of the microneedle sheet significantly increases the blood flow volume and blood flow velocity at the pigmented area where the sheet is applied. Therefore, it is believed that continued use of the sheet improves congestion and improves color tone.

Interestingly, about 20% of the subjects showed a more significant improvement in the a-value (redness) in the area around the cheek where the sheet was applied than in the area where the sheet was applied. The results of one of these subjects are shown in the table below.

Therefore, we investigated whether blood circulation around the area where the microneedle sheet was applied was promoted in several subjects.
In detail, a microneedle sheet was attached around the eye, and the blood flow condition in the surrounding area was determined by irradiating the living tissue with a laser to form speckles (spots) and tracking the changes in the speckles due to the movement of blood flow using a laser imaging speckle (PeriCam PSI: PERIMED, Sweden). The results are shown in Figure 1. It was found that the blood flow condition was promoted not only in the area where the microneedle sheet was attached, but also in the surrounding area. Therefore, it can be seen that the use of microneedles improves facial dullness caused by congestion.

By using the microneedle sheet of the present invention, simply by applying it to a part of the face and using it continuously for a specified period of time, it is possible to improve blood circulation not only in the part where the sheet is applied, but in the entire face, and brighten the overall facial tone.

Claims (6)

A cosmetic method for improving redness or yellowness around the eyes or cheeks by applying a microneedle sheet having a plurality of microneedles made of hyaluronic acid to areas under the eyes where dark circles form. The cosmetic method according to claim 1 , wherein the height of the microneedles is 50 to 200 μm. The cosmetic method according to claim 1 or 2, wherein the area of the microneedle sheet is 500 to 3,000 ^mm2 . A microneedle sheet preparation having a plurality of microneedles made of hyaluronic acid arranged thereon is applied to areas with dark circles under the eyes to improve redness or yellowness around the eyes or cheeks. The microneedle sheet preparation according to claim 4 , wherein the height of the microneedles is 50 to 200 μm. The microneedle sheet preparation according to claim 4 or 5 , having an area of 500 to 3,000 ^mm2 .