JP7468993B2 - Composition for inhibiting adhesion of fine particles - Google Patents

Description

The present invention relates to cosmetics, and in particular to cosmetics that can prevent skin damage caused by microparticles.

It is known that various chemical substances and xenobiotics float or fly in the air. Specifically, there are micro-scale particles such as particulate matter (PM) derived from smoke from automobiles, thermal power plants, incinerators, fireplaces, and cigarettes, ejecta from volcanic eruptions, and soil particles, pollen, dust, exhaust gases such as sulfur oxides (such as sulfur dioxide) and nitrogen oxides (such as nitrogen dioxide), and asbestos.

These microparticles cause air pollution and have a negative effect on the respiratory system when inhaled through the mouth and nose. They can also be taken into the body through the skin, which is the outermost layer of the body and is constantly exposed to the outside world, and there are concerns that they can cause skin problems and damage. For example, cigarette smoke is known to cause wrinkles and reduce skin transparency through the production of nitrogen oxides or active oxygen species, and certain organic compounds can cause skin inflammation. It has also been pointed out that microparticles of dust can affect genes by penetrating skin tissue with aromatic hydrocarbons adsorbed to their surface. Pollen from cedars, cypresses, and other trees can also cause allergic rhinitis (hay fever).

Therefore, attempts to prevent microparticles from adhering to the skin or penetrating the body through the skin and causing adverse effects are being considered. For example, Patent Document 1 describes how applying a composition having an α-gel structure to the skin surface to form a film prevents micropollutants from adhering to and penetrating the skin. Patent Document 2 describes how applying an amphoteric and anionic polymer-containing composition to the surface of the skin or clothing prevents pollen from adhering. Non-Patent Document 1 describes how a material that forms a conductive film obtained by polymerizing phosphorylcholine and acrylic acid monomer is used as a material for preventing the adhesion of microparticles.

Incidentally, in cosmetics, organically modified clay minerals obtained by modifying clay minerals such as bentonite with organic compounds are widely used as materials that improve the dispersion stability and rheology control of the system (Patent Document 3).

JP 2016-88866 A JP 2006-2147 A Patent No. 5044402

Miyazawa K. “Development of a shield technology to keep off air pollutants - Contribution to healthcare through a biocompatible polymer”, IFSCC Conference, Seoul (2017)

The materials of Patent Documents 1 and 2 and Non-Patent Document 1 were not necessarily satisfactory in suppressing adhesion of microparticles to the skin, and there was room for improvement. In particular, the polymer-based material of Non-Patent Document 1 sometimes caused an unpleasant feeling when applied to the skin.
In view of the above circumstances, an object of the present invention is to provide a technique for suppressing adhesion of microparticles to the skin surface.

The inventors noticed that clay mineral powder is uniformly arranged on the skin and that the powder is usually negatively charged, and discovered that by modifying the powder with a positively charged organic compound, a complex capable of forming a conductive coating on the skin can be obtained. They then came up with the idea that such a conductive coating is excellent at inhibiting the adhesion of microparticles, and thus completed the present invention.

That is, the present invention is as follows.
[1] A composition for inhibiting adhesion of fine particles, comprising a clay mineral modified with an organic compound, wherein the molecular size of the organic compound is 150% or less of the inter-charge distance of the clay mineral.
[2] The composition described in [1], wherein the theoretical modification rate of the organic compound with respect to the clay mineral is 50% or more.
[3] The composition according to [1] or [2], wherein the organic compound is a cationic or amphoteric compound.
[4] The composition described in [3], wherein the organic compound is lecithin.
[5] The composition according to any one of [1] to [4], wherein the clay mineral is selected from the group consisting of bentonite and hectorite.
[6] The composition described in [5], which is a topical skin preparation.
[7] The composition according to [6], which is a cosmetic.

The present invention provides a composition that has excellent properties for inhibiting adhesion of microparticles to the skin. Such a composition can be suitably used as a skin topical agent such as a cosmetic. The composition of the present invention also has excellent dispersibility, and is preferably in the form of an oil gel or emulsion.

1 is a graph showing the charge amount of a complex that forms a coating film of the composition of the present invention, and the charge transfer amount to (liberated) pollen after peeling off the coating film.

The composition of the present invention contains a clay mineral modified with an organic compound (hereinafter also referred to as the complex of the present invention).

The clay mineral in the complex of the present invention is usually a plate-like powder. Being plate-like makes it easier for the clay mineral to be uniformly arranged on a flat surface when applied to the skin, etc. As described below, the composition of the present invention can form a conductive film that is nearly electrically neutral. Normally, charged microparticles tend to adhere to the skin due to static electricity, but the film of the composition of the present invention applied to the skin can suppress the charge on the skin, thereby suppressing the adhesion of the microparticles. In this way, it is preferable for the clay mineral to be arranged on a flat surface in order to make it easier for the charge to escape.

Clay minerals usually carry an electric charge, which may be either positively or negatively charged, but are preferably negatively charged.
Examples of clay minerals include sucmetite-based hectorite, bentonite, montrealonite, kaolinite, illite, marine clay minerals (sea mud), desert rose clay minerals, and pascalite, and among these, bentonite and hectorite are particularly preferred.
Incidentally, each of these has a negative charge.
The charged sites of the clay mineral are arranged at equal intervals, and in plate-like powder, they are regularly arranged in a direction parallel to the plates. The distance between the charges can usually be calculated by the method disclosed in JP 2011-150037 A. For example, the distance between anion sites of Na-montmorillonite, which is the main component of bentonite, is about 1 nm.
Clay minerals of a size that can be normally incorporated into cosmetics can be used for the preparation of the complex. For example, clay minerals are usually aggregated when distributed as raw materials, and the volume average particle size of the secondary particles is preferably 0.5 to 1000 μm, but is not particularly limited thereto. In addition, clay minerals are generally subjected to treatments such as heating and stirring when incorporated and dispersed in compositions such as cosmetics, and the particle size is usually reduced. For example, by heating at about 25 to 80° C. and stirring at a high shear rate, the volume average particle size can be preferably 5 μm or less, 3 μm or less, and more preferably 1 μm or less. Here, the particle size is a value measured by a laser diffraction scattering method using a dry particle size distribution measuring device (e.g., LS 13 320 manufactured by Beckman Coulter, Inc.).

The organic compound in the complex of the present invention is electrically charged in order to efficiently modify the clay mineral, which is usually charged. The organic compound may be positively or negatively charged, but is preferably one that has a positive charge in water, more specifically, a cationic compound or an amphoteric compound.
That is, the clay mineral and organic compound constituting the complex of the present invention are preferably a combination of a negatively charged clay mineral and a cationic organic compound.

The organic compound in the complex of the present invention is of a size that is easily accommodated within the charge distance of the clay mineral in order to efficiently modify the charged sites of the clay mineral. Specifically, an organic compound is used whose molecular size is 150% or less, preferably 120% or less, more preferably 100% or less, and even more preferably 80% or less of the charge distance of the clay mineral. By using an organic compound of such a size, the modification rate of the complex of the present invention is high, and as a result, the neutralization rate described below is also high, thereby exerting an adhesion suppressing effect on microparticles.
In this specification, the term "molecular size" refers to the intermolecular distance, which is the square root of the molecular cross-sectional area, which is the reciprocal of the surface excess concentration calculated by measuring the surface tension using an automatic surface tensiometer CBVP-Z manufactured by Kyowa Interface Science Co., Ltd. Alternatively, the term may refer to a value calculated from the π-A curve (surface pressure-area curve) by measuring the surface film pressure of a monolayer (see Nobuyuki Tsubaki et al., Oil Chemistry, Vol. 41, No. 7, pp. 551-557, (1992)).

The organic compound in the complex of the present invention may be either naturally occurring or synthetic, but is preferably naturally occurring. Note that "naturally occurring" includes not only substances obtained from animals, plants, minerals, etc., but also compounds artificially produced from the same.
A preferred example of a naturally occurring lecithin is lecithin. Here, lecithin includes hydrogenated lecithin and non-hydrogenated lecithin, and either can be preferably used in the present invention as long as it satisfies a predetermined molecular size. In the case of hydrogenated lecithin (distearoylphosphatidylcholine), the molecular size is 0.71 nm.

Preferable examples of the organic compound in the complex of the present invention include compounds having a quaternary amino group. Specific examples include stearyl trimethyl ammonium chloride, dimethyl distearyl ammonium chloride, etc.

In the complex of the present invention, the mode of modification of the clay mineral with the organic compound includes via ionic bonds and covalent bonds.
The complexation can be carried out by mixing the organic compound used for modification with the clay mineral in an aqueous medium in a pH range in which the organic compound is cationized. For example, when lecithin is used as the organic compound, the pH is preferably 6 or less, more preferably 3 or less, and even more preferably 2 to 3. In an aqueous solution under such pH conditions, the cationized lecithin binds to the clay mineral to form a complex.

In the composite of the present invention, the theoretical modification rate of the organic compound to the clay mineral is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more, and the measured modification rate is preferably 40% or more, more preferably 55% or more, and even more preferably 70% or more.
Here, the modification rate is the molar amount of charge (usually cation) of the organic compound present per unit lattice plane of the complexed organic compound and clay mineral divided by the molar amount of exchangeable charge (usually anion) sites of the clay mineral, and represents the rate at which the organic compound fills the binding sites (usually charge sites) of the clay mineral.
The theoretical modification rate can be calculated from the molecular size of the organic compound and the charge distance of the clay mineral. Specifically, the surface of the clay mineral is considered to be a lattice with a spacing of the charge distance, and a circle with a diameter of the molecular size of the organic compound is closely packed on the lattice so as not to overlap. The theoretical modification rate can also be calculated by the method disclosed in JP 2011-150037 A.
In addition, the actual modification rate can be calculated by measuring the change in weight of the complex when heated using a thermal analyzer, and regarding the amount of weight loss due to exothermic oxidative decomposition as the amount of organic compound that had been complexed.

As described above, the composite of the present invention is generally a clay mineral modified with an organic compound having opposite charges, and is therefore close to neutral in charge. The "neutralization rate" (the closer to 100%, the greater the degree of neutralization) which represents the degree to which the charges are cancelled out and the composite obtained is electrically neutral may be synonymous with the modification rate described above.
In addition, the complex of the present invention is nearly neutral in charge, and specifically, when measured with an ESPERT analyzer (HOSOKAWA MICRON, EST-G) (applied voltage: 100 V, particle count: 1000, room temperature 25° C.),
±2°C, humidity 30%±3%, nitrogen gas pressure: 0.02 MPa), the absolute value of the charge amount of the composite particles is preferably 1.5 μC/g or less, more preferably 1.0 μC/g or less, even more preferably 0.7 μC/g or less, even more preferably 0.5 μC/g or less, and particularly preferably 0.4 μC/g or less.

The composition of the present invention has an effect of inhibiting adhesion of fine particles.
This is because the conductive coating formed by the composite of the present invention repels microparticles that are normally charged due to charge repulsion. However, this does not prevent the coating from simultaneously exerting a physical adhesion suppressing effect.

In this specification, microparticles refer to microscopic substances in general, and are usually substances that can have adverse effects on the skin. Examples of such substances include, but are not limited to, particulate matter (PM) derived from automobiles, thermal power plants, incinerators, fireplaces, and cigarette smoke, volcanic eruptions, and soil particles, as well as pollen, dust, exhaust gases such as sulfur oxides (sulfur dioxide, etc.), nitrogen oxides (nitrogen dioxide, etc.), asbestos, and other chemical substances and foreign substances in the body. In addition, microparticles are usually microscale particles, with a major axis of, for example, 50 μm or less. The shape of the particles is not particularly important.

In general, it is known that microparticles can cause physical irritation to the skin surface or can penetrate into the epidermis and cause irritation that promotes the release of inflammatory factors. The composition of the present invention can inhibit adhesion of microparticles to the skin, and therefore can inhibit inflammation caused by microparticles, and can be preferably used to prevent skin damage. Here, "skin damage" refers to any condition in which the skin is not healthy, such as a condition in which epidermal cells are stimulated and inflammation occurs due to the release of inflammatory factors, or a condition in which wrinkles, pigmentation, etc. occur as a result.

Therefore, the composition of the present invention is preferably in the form of an external skin preparation, and more preferably in the form of a cosmetic. The cosmetic may be, but is not limited to, a skin care cosmetic, a make-up cosmetic, or a hair care cosmetic.

The formulation of the composition of the present invention is not particularly limited and may be an emulsion, a lotion, an oil, a gel, an oil gel, a spray, a sheet mask, or the like.
The complex of the present invention exhibits excellent dispersibility even without blending other surfactants in the composition, and therefore is more preferably in the form of an emulsion or oil gel.

The content of the complex of the present invention in the composition of the present invention is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, and preferably 20% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, based on the total amount of the composition. For example, when the complex of the present invention is incorporated into a water-in-oil emulsion type composition, the content is preferably 0.5 to 5.0% by mass, more preferably 1.0 to 4.0% by mass, even more preferably 2.0 to 3.5% by mass, based on the total amount of the composition.
By setting the content within this range, it is easy to obtain the desired effect and the freedom in formulation design can be ensured.

The composition of the present invention may contain any optional ingredients used in ordinary skin preparations, etc., as long as they do not impair the effects of the present invention. Such optional ingredients include various active ingredients, oily ingredients, other surfactants, polyhydric alcohols, thickeners, powders, ultraviolet absorbers, etc.

The active ingredients include whitening ingredients, anti-wrinkle ingredients, anti-inflammatory ingredients, and extracts derived from other animals and plants.
The whitening ingredient is not particularly limited as long as it is one that is generally used in cosmetics, and examples thereof include 4-n-butylresorcinol, ascorbic acid glucoside, 3-O-ethyl ascorbic acid, arbutin, ellagic acid, kojic acid, linoleic acid, nicotinamide, 5,5'-dipropylbiphenyl-2,2'-diol, 5'-adenylic acid disodium, 4-methoxysalicylic acid potassium salt, hydroquinone, pantothenic acid, etc.

There are no particular limitations on the wrinkle-improving ingredient, so long as it is one that is generally used in cosmetics. Examples include sodium trifluoride isopropyl oxopropyl aminocarbonyl pyrrolidine carbonyl methyl propyl aminocarbonyl benzoyl aminoacetate, nicotinamide, vitamin A or its derivatives (retinol, retinal, retinoic acid, tretinoin, isotretinoin, tocopherol retinoate, retinol palmitate, retinol acetate, etc.), ursolic acid benzyl ester, ursolic acid phosphate, benzylic acid benzyl ester, and benzilic acid phosphate.

Anti-inflammatory ingredients include glycyrrhizic acid, glycyrrhetinic acid, allantoin, isopropylmethylphenol, clarinone, glabridin, salicylic acid, tocopherol acetate, tocopherol nicotinate, nicotinamide, pantothenic acid, pantothenyl alcohol, and salts or derivatives thereof, with glycyrrhizic acid and its salts, glycyrrhetinic acid and its salts, pantothenyl alcohol, and pantothenic acid and its salts being preferred.

The extracts derived from other animals and plants are not particularly limited as long as they are generally used in cosmetics and the like. For example, akebia extract, asparagus extract, avocado extract, amacha extract, almond extract, arnica extract, aloe extract, aronia extract, apricot extract, ginkgo extract, indian kinoko extract, fennel extract, udo extract, eizu extract, enmeiso extract, scutellaria root extract, phellodendron bark extract, coptis japonica extract, ginseng extract, hypericum extract, white lamb's foot extract, orange extract, kakyoku extract, pueraria root extract, chamomile extract, carrot extract, artemisia capillaris extract, kiwi extract, cucumber extract, guava extract, sophora root extract, gardenia extract, kumazasa extract, sophora flavescens extract, walnut extract, grapefruit ... Root extract, black rice extract, chlorella extract, mulberry extract, ginseng extract, alpinia gracilis extract, gentiana extract, geranium extract, black tea extract, burdock extract, rice extract, fermented rice extract, fermented rice bran extract, rice germ oil, cowberry extract, salvia extract, soapwort extract, bamboo extract, sanshou extract, zanthoxylum extract, shiitake mushroom extract, rehmannia root extract, lithospermum extract, perilla extract, linden extract, meadowsweet extract, peony extract, ginger extract, calamus root extract, birch extract, horsetail extract, stevia extract, fermented stevia, ivy extract, hawthorn extract, elderberry extract, yarrow extract, Mint extract, sage extract, mallow extract, cnidium extract, swertia bristlecone extract, soybean extract, tsinga extract, thyme extract, dandelion extract, tea extract, clove extract, tangerine extract, sweet tea extract, chili pepper extract, angelica extract, calendula extract, peach kernel extract, spruce extract, dokudami extract, tomato extract, natto extract, carrot extract, garlic extract, wild rose extract, hibiscus extract, burdock root extract, lotus extract, parsley extract, birch extract, witch hazel extract, sedge extract, cypress extract, loquat extract, coltsfoot extract, butterbur bud extract, bupleurum extract, butcher's broom extract, grape Examples of preferred extracts include grape seed extract, loofah extract, safflower extract, peppermint extract, linden extract, peony extract, hop extract, pine extract, mayonnaise extract, horse chestnut extract, skunk cabbage extract, soapberry extract, melissa extract, mozuku extract, peach extract, cornflower extract, eucalyptus extract, saxifrage extract, yuzu extract, lily extract, coix seed extract, mugwort extract, lavender extract, green tea extract, apple extract, rooibos tea extract, lychee extract, lettuce extract, lemon extract, forsythia extract, astragalus extract, rose extract, rosemary extract, Roman chamomile extract, royal jelly extract, and burnet extract.

The oily components include polar oils, volatile hydrocarbon oils, and the like.
Examples of polar oils include synthetic ester oils such as isopropyl myristate, cetyl octanoate, octyldodecyl myristate, isopropyl palmitate, butyl stearate, hexyl laurate, myristyl myristate, decyl oleate, hexyldecyl dimethyloctanoate, cetyl lactate, myristyl lactate, lanolin acetate, 2-ethylhexyl isononanoate, isocetyl stearate, isocetyl isostearate, cholesteryl 12-hydroxystearate, and ethyl di-2-ethylhexanoate. Examples of the fatty acid esters include ethylene glycol, dipentaerythritol fatty acid esters, N-alkyl glycol monoisostearate, neopentyl glycol dicaprate, diisostearyl malate, glyceryl di-2-heptylundecanoate, trimethylolpropane tri-2-ethylhexanoate, trimethylolpropane triisostearate, pentaneerythritol tetra-2-ethylhexanoate, glyceryl tri-2-ethylhexanoate, and trimethylolpropane triisostearate.

In addition, cetyl 2-ethylhexanoate, 2-ethylhexyl palmitate, glyceryl trimyristate, tri-2-heptylundecanoic acid glyceride, castor oil fatty acid methyl ester, oleic acid oil, cetostearyl alcohol, acetoglyceride, 2-heptylundecyl palmitate, diisobutyl adipate, N-lauroyl-L-
Other examples include 2-octyldodecyl glutamate, di-2-heptylundecyl adipate, ethyl laurate, di-2-ethylhexyl sebacate, 2-hexyldecyl myristate, 2-hexyldecyl palmitate, 2-hexyldecyl adipate, diisopropyl sebacate, 2-ethylhexyl succinate, ethyl acetate, butyl acetate, amyl acetate, triethyl citrate, and octyl methoxycinnamate.

Other natural oils include avocado oil, camellia oil, turtle oil, macadamia nut oil, corn oil, mink oil, olive oil, rapeseed oil, egg yolk oil, sesame oil, persic oil, wheat germ oil, sasanqua oil, castor oil, linseed oil, safflower oil, cottonseed oil, perilla oil, soybean oil, peanut oil, tea seed oil, kaya oil, rice bran oil, Chinese tung oil, Japanese tung oil, jojoba oil, germ oil, triglycerin, glyceryl trioctanoate, and glyceryl triisopalmitate.

Volatile hydrocarbon oils include alkanes having 12 to 16 carbon atoms, which may be linear or branched, such as isododecane and isohexadecane.

Examples of surfactants include anionic surfactants such as fatty acid soaps (sodium laurate, sodium palmitate, etc.), potassium lauryl sulfate, and alkyl triethanolamine ether sulfate; cationic surfactants such as stearyl trimethylammonium chloride, benzalkonium chloride, and laurylamine oxide; betaine surfactants (alkyl betaines, amido betaines, sulfobetaines, etc.); imidazoline amphoteric surfactants (2-cocoyl-2-imidazolinium hydroxide-1-carboxyethyloxy disodium salt, etc.); and amphoteric surfactants such as acyl methyl taurine; sorbitan fatty acid esters (sorbitan monostearate, sorbitan sesquioleate, etc.). , glycerin fatty acid esters (glyceryl monostearate, etc.), propylene glycol fatty acid esters (propylene glycol monostearate, etc.), hydrogenated castor oil derivatives, glycerin alkyl ethers, POE sorbitan fatty acid esters (POE sorbitan monooleate, polyoxyethylene sorbitan monostearate, etc.), POE sorbitan fatty acid esters (POE-sorbitan monolaurate, etc.), POE glycerin fatty acid esters (POE-glycerin monoisostearate, etc.), POE fatty acid esters (polyoxyethylene sorbitan monolaurate, etc.), triethylene glycol monooleate, POE distearate, etc.), POE alkyl ethers (POE 2-octyldodecyl ether, etc.), POE alkyl phenyl ethers (POE nonylphenyl ether, etc.), Pluronic (registered trademark) types, POE-POP alkyl ethers (POE-POP 2-decyltetradecyl ether, etc.), Tetronics, POE castor oil-hydrogenated castor oil derivatives (POE castor oil, POE hydrogenated castor oil, etc.), sucrose fatty acid esters, nonionic surfactants such as alkyl glucosides, etc.

Examples of polyhydric alcohols include polyethylene glycol, glycerin, 1,3-butylene glycol, erythritol, sorbitol, xylitol, maltitol, propylene glycol, dipropylene glycol, diglycerin, isoprene glycol, 1,2-pentanediol, 2,4-hexylene glycol, 1,2-hexanediol, and 1,2-octanediol.

Examples of thickening agents include guar gum, quince seed, carrageenan, galactan, gum arabic, pectin, mannan, starch, xanthan gum, curdlan, methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, methylhydroxypropyl cellulose, chondroitin sulfate, dermatan sulfate, glycogen, heparan sulfate, hyaluronic acid, sodium hyaluronate, tragacanth gum, keratan sulfate, chondroitin, mucoitin sulfate, hydroxyethyl guar gum, carboxymethyl guar gum, dextran, keratosulfuric acid, locust bean gum, succinoglucan, caronic acid, chitin, chitosan, carboxymethyl chitin, agar, polyvinyl alcohol, polyvinylpyrrolidone, carboxyvinyl polymer, alkyl-modified carboxyvinyl polymer, sodium polyacrylate, polyethylene glycol, and bentonite.

Examples of powders include powders such as mica, talc, kaolin, synthetic mica, calcium carbonate, magnesium carbonate, silicic anhydride (silica), aluminum oxide, and barium sulfate, which may be surface-treated; inorganic pigments such as red iron oxide, yellow iron oxide, black iron oxide, cobalt oxide, ultramarine, Prussian blue, titanium oxide, and zinc oxide, which may be surface-treated; pearlescent agents such as titanium mica, fish phosphorus foil, and bismuth oxychloride, which may be surface-treated; organic dyes such as Red No. 202, Red No. 228, Red No. 226, Yellow No. 4, Blue No. 404, Yellow No. 5, Red No. 505, Red No. 230, Red No. 223, Orange No. 201, Red No. 213, Yellow No. 204, Yellow No. 203, Blue No. 1, Green No. 201, Purple No. 201, and Red No. 204, which may be laked; and organic powders such as polyethylene powder, polymethyl methacrylate, nylon powder, and organopolysiloxane elastomer.

Examples of the ultraviolet absorber include para-aminobenzoic acid-based ultraviolet absorbers, anthranilic acid-based ultraviolet absorbers, salicylic acid-based ultraviolet absorbers, cinnamic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, sugar-based ultraviolet absorbers, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 4-methoxy-4'-t-butyldibenzoylmethane, and other ultraviolet absorbers.

The present invention will be described in more detail below with reference to examples, but it goes without saying that the present invention is not limited to these examples.

<Test Example 1> Preparation of Complex and Examination of Modification Rate (1) Confirmation of Cationic Region The pH region in which the organic compound used for modification is cationized in its aqueous solution was confirmed by zeta potential measurement (ELSZ-2, manufactured by Otsuka Electronics Co., Ltd.).

(2) Calculation of Molecular Size As the organic compounds, lecithin (hydrogenated lecithin Emulmetik 950, manufactured by Lucas Meyer Cosmetics), dimethyldioctadecylammonium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and lauryl betaine (Amphitol 24B, manufactured by Kao Corporation) were used.
For dimethyldioctadecylammonium chloride and lauryl betaine, the surface excess concentration was calculated by surface tension measurement (Kyowa Interface Science Co., Ltd., automatic surface tensiometer CBVP-Z). The molecular size was calculated from the molecular cross-sectional area, which is the reciprocal of the surface excess concentration.
The molecular size of lecithin was calculated from the π-A curve of a monolayer (Tsubaki, Nobuyuki et al., Oil Chemistry, Vol. 41, No. 7, pp. 551-557, (1992)).

(3) Preparation of complexes Various organic compounds (final concentration 1-25 mM), bentonite (Hojun, Bengel A) 8 g, 1N
Mix an appropriate amount of HCl or citric acid (for pH adjustment) and pure water (up to 800g) and heat at 80±5℃.
The mixture was stirred under a stirrer for 2 hours under agitation. After that, the mixture was washed with an aqueous HCl solution adjusted to pH 2.5-3, centrifuged, and the supernatant was discarded. This washing procedure was repeated three times. After washing, the residue was suction filtered and dried overnight in a vacuum dryer (80°C, -0.1 MPa) and then pulverized.

(4) Measurement of modification rate The change in weight upon heating was measured using a thermal analyzer (Rigaku TP2-R/TG-DTA), and the weight loss due to exothermic oxidative decomposition was regarded as the amount of complexed organic compounds, from which the degree of neutralization was calculated.
Measurement conditions: Temperature range 20-500°C, heating rate 5°C/min., in air Sample container: aluminum pan Modification rate was calculated as molar ratio of the composite organic compound/bentonite (converted into exchangeable charge sites) x 100 (%)

Table 1 shows the molecular size and modification rate of each organic compound.
The modification rates of dimethyldioctadecylammonium chloride (1.12 nm) and lauryl betaine (1.78 nm) were low, at 46.4% and 24.7%, respectively.
In the case of small lecithin (nm), the modification rate was as high as 92.3%, which means that the molecule was almost completely neutralized.

Test Example 2: Study of adhesion suppression effect (1) Sample The following powder particles were used.
Example 1: Lecithin-modified bentonite complex prepared in Test Example 1 Example 2: Dialkylammonium salt-modified bentonite "Benton 38V" (manufactured by Elementis Japan Co., Ltd.)
Comparative Example 1: Bentonite Comparative Example 2: Keratin Powder

(2) Measurement of the charge amount of powder particles (base material) Either the powder particles of the Example or Comparative Example were placed in a glass rod bottle and shaken for 3 minutes as a pre-charging treatment (forced charging). The charge amount of each charged powder particle was measured using an Espart Analyzer (Hosokawa Micron, EST-G). The measurement conditions were as follows: applied voltage: 100V, particle count: 1000, room temperature 25°C ± 2°C, humidity 30% ± 3%, nitrogen gas pressure: 0.02MPa.

(3) Measurement of the amount of charge transferred to pollen Pollen was placed in a glass rod bottle and shaken for 3 minutes as a pre-charging treatment (forced charging).
A 10% by mass ethanol solution of the powder particles of either the Example or Comparative Example was prepared, uniformly applied to an artificial leather (Sapplar) and dried, and then charged pollen was sprinkled on the artificial leather and nitrogen gas was sprayed to peel off the pollen. The charge of 1,000 liberated pollen grains was measured using an e-spert analyzer (measurement conditions were the same as in (2)). The absolute value of (charge amount of pollen after peeling - charge amount of pollen before sprinkling) was taken as the charge transfer amount to the pollen.

The results are shown in Figure 1. The horizontal axis represents the amount of charge on the powder particles (base), and the smaller the absolute value, the greater the degree of neutralization. The vertical axis represents the amount of charge transferred to the free pollen when the pollen is peeled off from the coating, and the greater the value, the more difficult it is for the pollen adhering to the coating to be peeled off. In the coating formed by modified bentonite (Examples 1 and 2), the amount of charge transferred to the pollen was small, confirming the adhesion suppression effect.

Claims (6)

A composition for suppressing adhesion of fine particles, comprising a clay mineral modified with an organic compound,
The molecular size of the organic compound is 150% or less of the charge distance of the clay mineral;
the organic compound is selected from the group consisting of lecithin and dialkylammonium salts;
The clay mineral is selected from the group consisting of bentonite and hectorite;
A composition (excluding a composition containing coltsfoot flower extract and a composition containing horseradish seed extract) in which a conductive coating formed by the clay mineral modified with the organic compound suppresses the static electricity of the skin, thereby inhibiting the adhesion of the microparticles. The composition according to claim 1, wherein the theoretical modification rate of the organic compound with respect to the clay mineral is 50% or more. The composition according to claim 1 or 2, wherein the dialkyl ammonium salt is dimethyl distearyl ammonium chloride. The composition according to any one of claims 1 to 3, wherein the microparticles are selected from the group consisting of particulate matter, pollen, dust, exhaust gas, and asbestos. The composition according to claims 1 to 4, which is a skin topical agent. The composition according to claim 5, which is a cosmetic.

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