JP7465477B2 - Emulsifiable clay oil composite powder - Google Patents

Description

Patent Law Article 30, Paragraph 2 applied Publication date: April 7, 2019 Publication address: http://www. be-ryu. net/

The present invention relates to a clay-oil composite powder that can be emulsified and dispersed by itself in an aqueous medium.

Emulsions are widely used in skin care cosmetics, medicines, foods, agricultural chemicals, paints, etc. For example, in skin care cosmetics, oil-in-water (O/W) type emulsions (so-called emulsions) obtained by emulsifying and dispersing oil in an aqueous medium are widely used to adjust the balance between moisture and oil in the skin.
These emulsions generally contain a surfactant as an emulsifier to stably disperse the oil in the aqueous medium.

Even in the case of an emulsion in which oil is emulsified and dispersed in an aqueous medium using an emulsifier, there is a limit to the improvement of long-term storage stability. In addition, due to the composition that combines water and organic matter (oil, surfactant), there is a concern that spoilage by microorganisms may occur depending on the storage environment.
The inventors of the present invention came up with the idea that if an emulsion can be dried and the dried product can be mixed with an aqueous medium at the time of shipment or use, so that the dried product can be redispersed (re-emulsified) in the aqueous medium by itself, the above-mentioned problem of long-term storage stability can be addressed. However, in reality, when an emulsion using a surfactant is subjected to a drying treatment, the emulsified state is destroyed to a level where it cannot be redispersed. As a result, it is difficult to obtain a redispersible dried product.

The present invention aims to provide a dispersoid material that contains oil and can be emulsified and dispersed in an aqueous medium by itself without special treatment for emulsification and dispersion (addition of an emulsifier, mechanical homogenization treatment).

The inventors of the present invention have conducted extensive research in light of the above problems. As a result, they have discovered that when emulsifying and dispersing oil in an aqueous medium, by using a water-swellable clay mineral instead of a surfactant and homogenizing this using a wet high-pressure treatment device, the oil and the water-swellable clay mineral become integrated and the clay mineral acts as an emulsifier, resulting in an emulsion with excellent emulsion stability. They have also discovered that the emulsion thus obtained can be dried and powdered, and that if this dried powder is mixed again in an aqueous medium, it will redisperse by itself to obtain an emulsion. The present invention has been completed based on these findings.

The above-mentioned object of the present invention has been achieved by the following means.
＜1＞
An emulsifiable clay-oil composite powder comprising a water-swellable clay and an oil, the hydration time being less than 30 minutes in the hydration test described below.
[Hydration test]
Put 100 mL of water at 25°C into a 200 mL Griffin beaker and leave it still. Drop 1.0 g of emulsifiable clay-oil composite powder onto the water surface. The time it takes for the re-emulsifiable dried emulsion dropped onto the water surface to become completely wetted with water is defined as the hydration time.
＜2＞
The emulsifiable clay oil composite powder according to <1>, which contains a thickener.
＜3＞
The emulsifiable clay oil composite powder according to <2>, wherein the thickener contains a water-soluble polymer.
＜4＞
The emulsifiable clay oil composite powder according to any one of <1> to <3>, wherein the oil component contains at least one of mineral oil, silicone oil, and squalane.
＜5＞
The emulsifiable clay-oil composite powder according to any one of <1> to <4>, wherein the water-swellable clay contains smectite.
＜6＞
In the emulsifiable clay oil composite powder, the content of the oil is 0.1 to 160 parts by mass per 100 parts by mass of the water-swellable clay. The emulsifiable clay oil composite powder according to any one of <1> to <5>.
＜７＞
A method for producing an emulsifiable clay-oil composite powder according to any one of <1> to <6>, comprising a step of subjecting a mixture of an aqueous medium, a water-swellable clay, and an oil component to wet high-pressure treatment to obtain an emulsion, and a step of drying the obtained emulsion.
＜8＞
A method for emulsifying and dispersing an emulsifiable clay oil composite powder, comprising mixing the emulsifiable clay oil composite powder according to any one of <1> to <6> with an aqueous medium, thereby emulsifying and dispersing the emulsifiable clay oil composite powder in the aqueous medium by the self-emulsifying property of the emulsifiable clay oil composite powder.

When the emulsifiable clay-oil composite powder of the present invention is mixed with an aqueous medium, it disperses in the aqueous medium by itself, and an emulsion can be obtained.

A preferred embodiment of the present invention will be described.

[Emulsifiable clay-oil composite powder]
The emulsifiable clay-oil composite powder of the present invention is a composite containing water-swellable clay and oil, and has a specific high hydration property as described below.When the emulsifiable clay-oil composite powder of the present invention is mixed with an aqueous medium, it can be emulsified and dispersed into an oil-in-water type by itself without special treatment (addition of emulsifier, homogenization by machine).In other words, the emulsifiable clay-oil composite powder of the present invention is a dispersoid material.
In the present invention, "emulsifiable" means, as described above, that the composition has the property of being able to emulsify and disperse by itself when mixed with an aqueous medium (self-emulsifiable).
In the present invention, the term "composite powder" or "composite" means that the water-swellable clay and the oil are not simply a mixture, but form an integral, inseparable structure.
In the present invention, the term "powder" broadly includes dry products. In other words, it means a solid such as a powder or granules, not a form that has a liquid medium and exhibits fluidity. "Powder" also includes those that have been molded into a desired size using a binder or press processing. In the present invention, the moisture content (moisture content) of "powder" is usually 20% by mass or less.
Each component constituting the emulsifiable clay-oil composite powder of the present invention will be described in turn, along with the hydration characteristics of the powder, the preparation method, and the emulsification and dispersion method.

<Water-swellable clay>
The emulsifiable clay oil composite powder of the present invention contains water-swelling clay (water-swelling clay mineral). The water-swelling clay is preferably a layered silicate. The general crystal structure of layered silicate is composed of unit crystal layers, which are negatively charged, and cations are incorporated between the layers to neutralize the negative charge. In addition, since these cations are capable of ion exchange, most layered silicates exhibit cation exchangeability and water swelling.
The water-swellable clay may be natural or synthetic, and may be unmodified or modified. The water-swellable clay constituting the re-emulsifiable dry emulsion of the present invention preferably contains at least one type of smectite, and more preferably is composed of at least one type of smectite. The smectite as the water-swellable clay used in the present invention may contain impurities that natural clay minerals may normally have. The smectite is preferably natural smectite, synthetic clay (preferably synthetic smectite), or a mixture thereof.

Examples of natural smectite include naturally occurring hectorite, montmorillonite, beidellite, saponite, stevensite, nontronite, sauconite, etc., and one or more of these can be used.
It is also preferable to use bentonite containing montmorillonite as the natural smectite. Bentonite is an inorganic clay mineral that occurs naturally and is therefore highly safe. In addition, bentonite is not decomposed by microorganisms in the soil and is stable for a long period of time, and has the advantage of being inexpensive. Commercially available bentonite can be used, and an example of the commercially available product is Kunipia-F (manufactured by Kunimine Kogyo Co., Ltd.), which is made by refining natural bentonite.

Synthetic clay can be synthesized by conventional methods, or commercially available products may be used. Examples of commercially available products include Sumecton-SA (manufactured by Kunimine Kogyo Co., Ltd.) as synthetic saponite, and Sumecton-SWN (manufactured by Kunimine Kogyo Co., Ltd.) as synthetic hectorite.

The water-swellable clay preferably contains saponite or montmorillonite, and more preferably is saponite or montmorillonite.

<Oil content>
The emulsifiable clay oil composite powder of the present invention contains oil. In the present invention, the term "oil" is used in a broader sense than usual. That is, when the term "oil" is used in the present invention, it means that it broadly includes components that are incompatible with water. Here, "incompatible with water" means that when mixed with water at 25°C, it does not mix with water, and water and oil are in a relationship in which they exist in independent phases. The components constituting the oil may be one type or two or more types. In addition, the "oil" may contain a lipophilic component. The lipophilic component is a component that is soluble in the oil and also compatible with water. Specific examples of the lipophilic component are ceramide, cholesterol, protein derivatives, lanolin, lanolin derivatives, lecithin, vegetable aroma oils, oily bases such as antibacterial components, pigments, etc. When the oil contains a lipophilic component, the whole including the lipophilic component is the "oil" defined in the present invention.
The oil is preferably liquid at room temperature. Specific examples of the oil include mineral oils such as indodecane, silicone oils such as cyclopentasiloxane, squalane, liquid paraffin, liquid isoparaffin, olive oil, rice germ oil, soybean oil, sesame oil, rapeseed oil, sunflower oil, cod liver oil, ester oil, etc. Among them, the oil constituting the emulsifiable clay oil composite powder of the present invention preferably contains at least one of mineral oil, silicone oil, and squalane, and more preferably at least one of mineral oil, silicone oil, and squalane. The melting point of the oil is preferably lower than the melting point of the water-swellable clay.
In addition, as described below, the water-swellable clay has a structure surrounding the oil, which is thought to contribute to improved heat resistance.

In the emulsifiable clay-oil composite powder of the present invention, the content of the oil is appropriately set according to the purpose. Usually, the content of the oil is 0.1 to 160 parts by mass relative to 100 parts by mass of the water-swellable clay. By setting the content of the oil to 0.1 to 160 parts by mass, the emulsifiable clay-oil composite powder can be sufficiently improved in emulsification dispersibility in an aqueous medium, and the effective amount of oil in the resulting emulsion can be secured according to the purpose. In the emulsifiable clay-oil composite powder of the present invention, the content of the oil is more preferably 1 to 150 parts by mass, and even more preferably 5 to 130 parts by mass, relative to 100 parts by mass of the water-swellable clay. It may also be 10 to 120 parts by mass, or it may be 20 to 100 parts by mass, or it may be 30 to 80 parts by mass, or it is also preferable that it is 40 to 60 parts by mass.

The emulsifiable clay oil composite powder of the present invention may contain a thickener. By including a thickener, the dispersion stability of the emulsion obtained by emulsifying and dispersing the hydratable powder of the present invention in an aqueous medium can be further improved. Preferred examples of the thickener include water-soluble polymers such as xanthan gum, carrageenan, guar gum, and water-soluble starch, and cellulose nanofibers. One or more water-soluble polymers can be used as the thickener.

The emulsifiable clay oil composite powder of the present invention may contain water-soluble components other than the thickener, as long as the effect of the present invention is not impaired. These components are appropriately selected according to the purpose of the application of the emulsifiable clay oil composite powder. For example, if the application is a skin care cosmetic, polyhydric alcohols such as glycerin, diglycerin, polyethylene glycol, sorbitol, maltitol, and isomaltitol, sugars such as lactose, fructose, sucrose, maltose, trehalose, and isomaltooligosaccharide, organic or inorganic salts such as pyrrolidone carboxylate, citrate, malate, and salt, pH adjusters, bactericides, chelating agents, antioxidants, blood circulation promoters, ultraviolet absorbers, ultraviolet scattering agents, natural extracts derived from animals and plants, ascorbic acid and its derivatives, flavonoids such as anthocyanin and its derivatives, water-soluble vitamins, amino acids, photosensitizers, dyes, pigments, and fragrances can be blended.

The emulsifiable clay oil composite powder of the present invention may further contain other components within the range that does not impair the effects of the present invention. For example, it may contain an emulsifier such as a surfactant. On the other hand, since the water-swellable clay acts as an emulsifier and shows sufficient dispersibility, it is also preferable for the emulsifiable clay oil composite powder of the present invention to be in a form that does not contain an emulsifier such as a surfactant.

<Hydration characteristics>
The emulsifiable clay oil composite powder of the present invention has high wettability with water, and the hydration time in the hydration test described below is less than 30 minutes.

- Hydration test -
Put 100 mL of water at 25°C into a 200 mL Griffin beaker and leave it still. Drop 1.0 g of emulsifiable clay-oil composite powder onto the water surface. The time it takes for the re-emulsifiable dried emulsion dropped onto the water surface to become completely wetted with water is defined as the hydration time.
Here, "wet with water" means that the powder is immersed in water, and that the powder on the water surface becomes wet due to capillary action while remaining on the water surface.

By making the hydration time in the above hydration test less than 30 minutes, it is possible to show sufficiently high emulsification and dispersibility when mixed with an aqueous medium. In the above hydration test, it is preferable that no oil is liberated in the water. However, even if a part of the oil is liberated, as long as the oil is sufficiently secured in the dispersoid, the effect of the present invention is enjoyed, and such emulsifiable clay-oil composite powder is also included in the present invention.
The hydration time in the hydration test is preferably less than 20 minutes, more preferably less than 10 minutes, even more preferably less than 5 minutes, particularly preferably less than 3 minutes, even more preferably less than 2 minutes, and most preferably less than 1 minute. The shorter the hydration time, the faster the emulsion dispersion speed when mixed into an aqueous medium.
In addition, when the particles of the emulsifiable clay-oil composite powder are bound together by a binder or by press processing, etc., they shall be powderized before being subjected to the hydration test.

<Preparation of emulsifiable clay-oil composite powder>
The method for preparing the emulsifiable clay-oil composite powder of the present invention is not particularly limited as long as it can obtain a composite powder exhibiting the above-mentioned hydration characteristics.Preferably, the mixture containing the water-swellable clay, the oil, and other components added as necessary is subjected to wet high-pressure treatment using an aqueous medium as a medium liquid to obtain an oil-in-water emulsion, and the oil-in-water emulsion is dried to remove the aqueous medium.
The above-mentioned wet high-pressure treatment method is a method in which pressure energy is converted into kinetic energy to generate a jet flow, and the oil is homogenized by the shear force generated in the jet flow, and the oil is emulsified and dispersed in an aqueous medium to generate an emulsion. The wet high-pressure treatment itself is known, and for example, Japanese Patent No. 5791142 and Japanese Patent No. 5972434 can be referred to. As a wet high-pressure treatment device, for example, NEW BERYU MINI manufactured by Biryu Co., Ltd. is commercially available.
It is believed that by adopting wet high-pressure treatment, the strong shear force generated by the jet flow caused by the high pressure cuts open the layers of the water-swellable clay, which in turn makes the interaction between the oil and the water-swellable clay more efficient, causing the water-swellable clay to act like an emulsifier, making it possible to obtain a stable emulsion.

The method for drying the oil-in-water emulsion obtained by wet high-pressure treatment is not limited to a specific method. Specific examples of the drying method include heat drying, freeze drying, and vacuum drying. In the case of heat drying, the heating temperature is preferably 40 to 200°C, and more preferably 50 to 100°C.

The aqueous medium of the oil-in-water emulsion obtained by wet high-pressure treatment contains water and may further contain a water-soluble organic solvent if necessary. This aqueous medium is preferably 50% by mass or more water. There are no particular limitations on the water-soluble organic solvent, and it is selected appropriately depending on the purpose. For example, in the case of skin care cosmetics, examples of alcohols that can be used include ethanol, propanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-butylene glycol, pentamethylene glycol, hexylene glycol, hexylene glycol, 1,3-butanediol, 1,4-butanediol, glycerin, diglycerin, and polyglycerin, and one or more of these can be used.

There are no particular limitations on the concentration of components other than the aqueous medium in the oil-in-water emulsion obtained by wet high-pressure treatment. It is usually 0.1 to 50% by mass.

<Emulsification and dispersion of emulsifiable clay-oil composite powder>
The emulsifiable clay oil composite powder of the present invention can be naturally redispersed by itself to obtain an emulsion by simply mixing with an aqueous medium. In other words, no special treatment (addition of emulsifier, homogenization by machine) is required for emulsification dispersion. The preferred form of the aqueous medium for emulsifying and dispersing the emulsifiable clay oil composite powder of the present invention is the same as the aqueous medium of the oil-in-water emulsion obtained by wet high pressure treatment described above.

The particle size distribution of the oil in the oil-in-water emulsion obtained by emulsifying and dispersing the emulsifiable clay-oil composite powder of the present invention in an aqueous medium preferably exhibits a single peak.

The emulsion obtained by emulsifying and dispersing the emulsifiable clay oil composite powder of the present invention can enjoy the excellent functionality inherent to water-swellable clay. For example, when the emulsion is used as a cosmetic or body care product, it can achieve a non-sticky, smooth, and refreshing feel, spread well on the skin surface, and have cleansing properties, and can provide a good texture and finish after use. In particular, smectites such as montmorillonite and saponite can provide the above-mentioned favorable feel while being inexpensive, and also show the same thickening effect as polymer thickeners, and can provide advantages such as improved drainage when the cosmetic is taken out of the container.

Next, the present invention will be described in more detail based on the following examples, but the present invention is not limited in any way by these examples except as defined in the present invention.

[Examples 1 to 6]
5 g of oil shown in Table 1 was added to 995 g of aqueous dispersion in which the water-swellable clay shown in Table 1 was dispersed in water at a concentration of 2.5% by mass, and mixed for 10 minutes at 1000 rpm using a stirrer (TORNADO SM-102 manufactured by AS ONE). The resulting mixture was homogenized by the shear force of a high-pressure jet stream using a wet high-pressure processor (NEW BERYU MINI manufactured by Biryu Co., Ltd.) to obtain an oil-in-water emulsion. 500 g of the mixture was weighed out and subjected to heat drying (about 105 ° C) or freeze drying as shown in Table 1. Thus, 15 g of emulsifiable clay-oil composite powder was obtained.
In Table 1, "Sumecton-SA" (manufactured by Kunimine Kogyo Co., Ltd.) is synthetic saponite, "Kunipia-F" (manufactured by Kunimine Kogyo Co., Ltd.) is bentonite, and "Sumecton-SWN" (manufactured by Kunimine Kogyo Co., Ltd.) is synthetic hectorite.

[Comparative Examples 1 and 2]
5 g of squalane was added to 995 g of an aqueous solution in which TWEEN 20 was dissolved at a concentration of 2.5% by mass, and the mixture was mixed for 10 minutes at 1000 rpm using a stirrer (TORNADO SM-102 manufactured by AS ONE). The resulting mixture was homogenized by the shear force of a high-pressure jet stream using a wet high-pressure processor (NEW BERYU MINI manufactured by Biryu Co., Ltd.) to obtain an oil-in-water emulsion. 500 g of the mixture was weighed out and subjected to thermal drying (about 105°C) or freeze drying. However, water and squalane separated during drying, and no powder was obtained.

The hydration and redispersibility of the emulsifiable clay-oil composite powders of Examples 1 to 6 were evaluated as follows.

<Evaluation of hydration>
Hydration was evaluated according to the CIPAC MT53 Hydration Test Method in the Pesticide Formulation Guide. First, 100 mL of distilled water at 25°C was poured into a 200 mL Griffin beaker and left to stand. 1.0 g of each emulsifiable clay oil composite powder obtained in each of Examples 1 to 6 was weighed out carefully so as not to compress it, and dropped from the edge of the beaker to the water surface at once. At this time, care was taken not to give excessive impact to the water surface. The time from when the hydratable powder was dropped onto the water surface until the hydratable powder was completely wetted with water (the powder on the water surface was wetted by capillary action while remaining on the water surface, or was immersed in water until all the hydratable powder was wetted with water) was measured to the second unit, and the measured time was taken as the hydration time.
After complete wetting, the state of oil released into the water was observed.
The results were evaluated according to the following criteria.

- Hydration time -
A: Less than 5 minutes B: 5 to 10 minutes C: 10 to 30 minutes D: 30 minutes or more

- Release of oil -
A: No release of oil is observed.
B: Release of oil is observed.

<Evaluation of redispersibility>
0.1 g of the emulsifiable clay oil composite powder of Examples 1 to 6 was added to 49.9 g of water and stirred. The state of the resulting mixed liquid was observed and the redispersibility was evaluated according to the following evaluation criteria.

-Redispersibility-
A: The product is emulsified and dispersed in oil-in-water, with no precipitation occurring.
B: The mixture is emulsified and dispersed in oil-in-water, with slight precipitation.
C: An emulsified dispersion state was not formed, and precipitation occurred.

<Evaluation of particle size distribution>
For the oil-in-water emulsions prepared in the above evaluation of redispersibility, the wet particle size distribution of the oil content was measured using a Horiba LA-950V2 and evaluated according to the following criteria.
A: The wet particle size distribution shows a single peak.
B: The wet particle size distribution shows multiple peaks.
In addition, the median diameter (d50) was determined.

The results are shown in Table 1 below.

The emulsifiable clay-oil composite powders of Examples 1 to 6 were composites of water-swellable clay and oil, which were easily compatible with water and had excellent redispersibility in water (self-emulsifiable properties).
In addition, the particle size distribution of the oil in the emulsion after redispersion was monodisperse with a single peak, and this particle size distribution was similar to that of the emulsion before drying. In addition, the particle size (d50) of the oil in the emulsion after redispersion was sufficiently small. These facts also support the fact that the emulsifiable clay-oil composite powder of the present invention has excellent self-emulsifying properties.

Claims (8)

An emulsifiable clay-oil composite powder comprising a water-swellable clay and an oil, the hydration time being less than 5 minutes in the hydration test described below.
[Hydration test]
Put 100 mL of water at 25°C into a 200 mL Griffin beaker and leave it still. Drop 1.0 g of emulsifiable clay-oil composite powder onto the water surface. The time it takes for the re-emulsifiable dried emulsion dropped onto the water surface to become completely wetted with water is defined as the hydration time. The emulsifiable clay-oil composite powder according to claim 1, which contains a thickener. The emulsifiable clay-oil composite powder according to claim 2, wherein the thickener contains a water-soluble polymer. An emulsifiable clay-oil composite powder according to any one of claims 1 to 3, wherein the oil component contains at least one of mineral oil, silicone oil, and squalane. The emulsifiable clay-oil composite powder according to any one of claims 1 to 4, wherein the water-swellable clay contains smectite. The emulsifiable clay-oil composite powder according to any one of claims 1 to 5, wherein the content of the oil in the emulsifiable clay-oil composite powder is 0.1 to 160 parts by mass per 100 parts by mass of the water-swellable clay. A method for producing an emulsifiable clay-oil composite powder according to any one of claims 1 to 6, comprising the steps of subjecting a mixture of an aqueous medium, a water-swellable clay, and an oil component to wet high-pressure treatment to obtain an emulsion, and drying the emulsion thus obtained. The emulsifiable clay oil composite powder according to any one of claims 1 to 6 is mixed with an aqueous medium, and the emulsifiable clay oil composite powder is emulsified and dispersed in the aqueous medium by the self-emulsifying property of the emulsifiable clay oil composite powder. A method for emulsifying and dispersing an emulsifiable clay oil composite powder.