JP-7857192-B2 - Oil-in-water emulsion composition

Inventors

• 井岡 千紘
• 古勢 美緒
• 寺西 諒真
• 忍田 亜希子
• 力丸 あゆみ
• 山崎 貴史
• 辻 俊一

Assignees

• 株式会社ファンケル
• キリンホールディングス株式会社

Dates

Publication Date

20260512

Application Date

20220905

Claims (7)

1. Oil-in-water emulsion composition containing the following components (a) to (c); (a) Particles comprising a polymer having a hydrophobic portion having a cationic group containing hydrophobic monomer units, and a hydrophilic portion containing at least a hydrophilic monomer unit represented by the following formula (I), (b) water, and (c) oil.
2. The oil-in-water emulsion composition according to claim 1, wherein the oil is one or more selected from hydrocarbon oils, silicone oils, and ester oils.
3. The oil-in-water emulsion composition according to claim 1 or 2, wherein the content of the oil agent in the oil-in-water emulsion composition is 55% by mass or more and 80% by mass or less.
4. The oil-in-water emulsion composition according to claim 1 or 2, wherein the content of a surfactant as an emulsifier in the oil-in-water emulsion composition is less than 1% by mass .
5. The oil-in-water emulsion composition according to claim 1 or 2, wherein the cationic group is derived from a cationic radical polymerization initiator.
6. The cationic radical polymerization initiator is 2,2'-[diazen-1,2-diylbis(propane-2,2-diyl)]bis(1,3-dimethyl-4,5-dihydro-1H-imidazole-3-ium)=ditrifluoromethanesulfonate (ADIP), 2,2'-[diazen-1,2-diylbis(propane-2,2-diyl)]bis(1,3-dimethyl-4,5-dihydro-1H-imidazole-3-ium)=di The oil-in-water emulsion composition according to claim 5, comprising one or more selected from the group consisting of chloride (ADIP-Cl), 2,2'-azobis(2-methylpropionamidine)dihydrochloride (V-50), 2,2'-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (VA-044), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane] (VA-061).
7. The oil-in-water emulsion composition according to claim 1 or 2, wherein the hydrophilic portion further comprises monomer units represented by the following formula (II), and the ratio of the number of monomer units represented by formula (I) to the total number of monomer units represented by the following formula (II) (degree of saponification) is 70% or more and 99% or less.

Description

This invention relates to an oil-in-water emulsion composition having excellent usability. Emulsified compositions, such as oil-in-water and water-in-oil compositions, generally maintain a stable state where aqueous and oily components are finely mixed due to the emulsifying action of the surfactants used. Such emulsions are widely used in daily necessities, personal care products, and biomedical applications. However, using large amounts of surfactants in emulsions can cause problems such as stickiness and irritation when applied directly to the skin or other parts of the body. Furthermore, many consumers are concerned about the effects of surfactants that can be absorbed by the body. Therefore, it is desirable to minimize the amount of surfactants used in emulsions. Against this backdrop, attempts are being made to utilize additives with emulsifying properties other than surfactants in oil-in-water emulsion compositions. One such attempt that is attracting attention is the development of oil-in-water emulsion compositions emulsified by placing solid particles near the interface between the oil and aqueous phases. Figure 1 is a schematic comparison of an emulsion containing a surfactant and an oil-in-water emulsion composition (hereinafter also referred to as "oil-in-water emulsion composition emulsified by solid particles"), which is emulsified by placing solid particles near the interface between the oil and aqueous phases. While the present invention is not bound by any theory, generally, oil-in-water emulsion compositions emulsified by solid particles are sometimes called Pickering emulsions, and it is presumed that mineral particles or amphiphilic organic particles are present at the interface of aqueous or oily droplets, stabilizing the structure of the droplets. As mentioned above, there has been a certain degree of demand for emulsified compositions that do not use surfactants. An example of an oil-in-water composition that substantially does not contain surfactants as emulsifiers is disclosed in Patent Document 1, for instance, which includes (1) an oil phase, (2) an aqueous phase, and (3) a finely milled inorganic pigment selected from the group consisting of amphiphilic metal oxides having an average particle size of less than 200 nm. Special Publication No. 2001-518111 This is a schematic comparison diagram of emulsions using surfactants and emulsions using solid particles. The embodiments for carrying out the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below are for illustrative purposes only, and the following description in these embodiments should not be construed as limiting the language of the claims. <Oil-in-water emulsion composition> The oil-in-water emulsion composition of this embodiment comprises (a) particles containing a polymer having a hydrophobic portion having a cationic group containing hydrophobic monomer units and a hydrophilic portion containing at least predetermined hydrophilic monomer units, (b) water, and (c) an oil. The oil-in-water emulsion composition of this embodiment has a good texture after application and also exhibits excellent emulsification stability as an oil-in-water emulsion composition, and can therefore be used in general applications, particularly in cosmetics, pharmaceuticals, and other fields that come into direct contact with the human body. From the viewpoint of improving the feel after application, it is preferable that the oil-in-water emulsion composition of this embodiment substantially does not contain surfactants or inorganic oxides (usually fine inorganic particles with an average primary particle diameter of about 1 nm to 200 nm) as emulsifiers. "Substantially does not contain" means, for example, that the content in the oil-in-water emulsion composition of this embodiment is less than 1% by mass. Furthermore, the oil-in-water emulsion composition of this embodiment can be prepared without using equipment that generates strong industrial-grade external forces, such as ultrasonic devices or homogenizers, and heat treatment for stabilizing the dispersion state is not necessarily required. Therefore, this embodiment can also contribute to reducing the environmental burden during the preparation of the oil-in-water emulsion composition. However, the present invention also includes oil-in-water emulsion compositions prepared using ultrasonic devices, homogenizers, etc., within its scope of rights. [(a) Particles] The oil-in-water emulsion composition of this embodiment contains particles comprising a polymer having hydrophobic monomer units, a hydrophobic portion having a cationic group, and a hydrophilic portion containing predetermined hydrophilic monomer units. The particle content in the oil-in-water emulsion composition of this embodiment is preferably 0.1% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 4.0% by mass or less. B