HK1240098B - Chemically anisotropic powder, and cosmetic composition containing same - Google Patents

Description

Chemically anisotropic particles and cosmetic compositions thereof

【Technical field】

The present invention relates to chemically anisotropic powders having improved emulsion dispersion stability, and cosmetic compositions thereof.

[Background Technology]

Emulsion systems using conventional surfactants can only be stably produced without de-emulsification phenomena such as creaming, flocculation, aggregation, or breakage when the particle size is uniform and as small as a few microns. Therefore, much current research focuses on the production of emulsion formulations containing uniformly sized emulsified particles as small as a few microns or smaller.

However, producing such emulsion formulations requires stabilizing the interfacial film and reducing the fluidity of the emulsion particles. The interfacial film is created by using a larger amount of surfactant than the oil content, while the fluidity of the emulsion particles is reduced by increasing the viscosity with thickeners or waxes. This leads to numerous problems, such as an unpleasant feeling of stickiness and stiffness during use, limited viscosity, and the formation of sludge caused by the use of thickeners, making it difficult to provide various formulations.

At the same time, many methods for preparing fine particles of various shapes and sizes (nanoscale, microscale, etc.) have been reported. In particular, spherical particles containing polymers have high applicability, as their size and shape can be controlled depending on the preparation method. For example, a Pickering emulsion using spherical particles has been proposed to form stable microemulsified particles. Furthermore, attempts have been made to impart amphiphilicity (i.e., hydrophilic and hydrophobic properties) to spherical particles, resulting in new anisotropic powders. This can be exemplified by Janus spherical particles. However, such spherical particles have limited chemical anisotropy due to their morphological limitations. In other words, although the particles are morphologically anisotropic and can be hydrophobic or hydrophilic overall, they possess limited chemical anisotropy. Furthermore, due to the difference in specific gravity caused by the size of the emulsion particles, phase separation may occur (in an oil/water formulation (O/W formulation), the upper layer will cream; in a water/oil formulation (W/O formulation), the lower layer will precipitate).

Under these circumstances, there is a need to provide a cosmetic composition that can improve the dispersibility of microemulsified particles to prevent phase separation even when a small amount of a thickener (such as carbomer) is used, and also provide a cosmetic composition comprising the anisotropic powder.

[Summary of the invention]

[Technical Issues]

The present invention provides a solution to a technical problem, namely, providing a chemically anisotropic powder, utilizing the anisotropic powder to increase electrostatic repulsion, so that the increase in external viscosity caused by the use of thickeners and waxes can be minimized and the dispersion state can be maintained.

Another technical problem to be solved by the present invention is to provide a cosmetic composition comprising micronized emulsified particles, which is a stable formulation that does not cause aggregation even when the emulsified particles have non-uniform sizes and has improved dispersion stability between the particles to reduce the amount of external thickener used.

Another technical problem to be solved by the present invention is to provide a low-viscosity emulsion cosmetic composition with a high oil content, which exhibits emulsion-like softening and moisturizing effects and has a low viscosity or non-sticky emulsion formulation like a lotion or toner to provide excellent spreadability and usage experience.

[Technical Solution]

In a general aspect, a chemically anisotropic powder with improved dispersibility is provided, comprising first polymer spheres and second polymer spheres, wherein the first polymer spheres and the second polymer spheres are bonded to each other in a structure in which one polymer sphere at least partially penetrates the other polymer sphere; the first polymer spheres have a core-shell structure; the shell has functional groups; and at least one of the first polymer spheres and the second polymer spheres is negatively or positively charged.

According to one embodiment, at least one of the first polymer sphere and the second polymer sphere comprises an ionic vinyl polymer.

According to another embodiment, the ionic vinyl polymer may be sodium 4-vinylbenzene sulfonate polymer.

According to another embodiment, the cores of the second polymer sphere and the first polymer sphere include a vinyl polymer, and the shell of the first polymer sphere includes a copolymer of a vinyl monomer having a functional group.

According to yet another embodiment, the vinyl polymer may include polystyrene.

According to yet another embodiment, the functional group may be siloxane.

According to yet another embodiment, the chemically anisotropic powder may have a symmetrical shape, an asymmetrical snowman shape, or an asymmetrical reverse snowman shape depending on where the first polymer sphere and the second polymer sphere are bonded to each other.

According to another embodiment, the chemically anisotropic powder may have a particle size of 100-1500 nanometers.

In another general aspect, a cosmetic composition comprising a chemically anisotropic powder having improved dispersibility is provided.

According to one embodiment, the chemically anisotropic powder can be formed into micro-emulsified particles with a size of 5-200 microns.

According to another embodiment, the chemically anisotropic powder may be present in an amount of 0.1-15 wt % based on the total weight of the cosmetic composition.

According to another embodiment, the cosmetic composition may comprise an oil content of 15-30 wt % based on the total weight of the cosmetic composition.

According to yet another embodiment, the cosmetic composition may have a low viscosity emulsion formulation of 300 centipoise or less.

[Beneficial Effects]

According to embodiments of the present disclosure, the interface of anisotropic powders is modified to minimize the amount of thickener required to disperse the emulsified particles. This results in an emulsion system that achieves homogeneous dispersion through repulsive forces between the powdered emulsified particles without the use of any thickener. This emulsion system prevents phase separation even with minimal thickener and provides a skin-softening formulation with a high oil content and low viscosity, a feat not achievable with existing technologies.

Furthermore, according to embodiments of the present disclosure, a cosmetic composition comprising a chemically anisotropic powder with improved dispersibility is provided. Thus, the cosmetic composition is a stable formulation comprising micronized emulsified particles that does not aggregate even when the emulsified particles have non-uniform sizes. Furthermore, the improved inter-particle dispersion stability reduces the amount of external thickeners used.

Furthermore, according to an embodiment of the present disclosure, a low-viscosity emulsion cosmetic composition with a high oil content is provided, which exhibits an emulsion-like softening effect and moisturizing effect, and has a low viscosity or non-sticky emulsion formulation like a lotion or toner to provide excellent spreadability and usage feel.

【Brief Description of the Drawings】

FIG1 shows a schematic diagram of the formation of chemically anisotropic powders.

FIG2 is a graph showing viscosity measurement results in the high-oil content, low-viscosity emulsion cosmetic composition disclosed herein (from left to right, (a) represents a conventional skin softening formulation, (b) represents the formulation of Preparation Example 1, and (c) represents a conventional skin softening formulation).

FIG3 shows microscopic images of the high-oil-content, low-viscosity emulsion cosmetic composition disclosed herein (the left image (a) is taken at a magnification of 200 times, while the right image (b) is taken at a magnification of 400 times, which demonstrates that the chemically anisotropic powder disclosed herein forms microemulsified particles having a size of tens of microns, ranging from at least 15 microns to 60 microns).

FIG4 shows the evaluation results of the formulation stability of the emulsion cosmetic composition disclosed herein (from left to right, (a) is a sample stored at room temperature, (b) is a sample stored at 45° C., (c) is a sample stored at 60° C., and (d) is a sample after refrigeration for 4 weeks).

Figure 5 shows the results of a comparison of the moisturizing effects of (a) a high-oil, low-viscosity emulsion cosmetic composition (Preparation Example 1) with various ingredients (b) conventional emollients (c) conventional lotions, and (d) conventional creams. (From left to right, the long bar (a) represents the cosmetic composition of Preparation Example 1, (b) represents a conventional emollient, (c) represents a conventional lotion, and (d) represents a conventional cream.)

Figure 6 shows the results of a comparison of skin gloss between (a) a high-oil, low-viscosity emulsion cosmetic composition (Preparation Example 1) and various ingredients: (b) a conventional skin softener, (c) a conventional skin lotion, and (d) a conventional cream. (From left to right, the long bar (a) represents the cosmetic composition of Preparation Example 1, (b) a conventional skin softener, (c) a conventional skin lotion, and (d) a conventional cream.)

[Specific implementation method]

Exemplary embodiments will now be described more fully below with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the present invention may be presented in many different forms and should not be construed as being limited to the exemplary embodiments set forth herein. Furthermore, these embodiments are provided to make the present invention thorough and complete and to fully convey the scope of the invention to those skilled in the art. In the accompanying drawings, the shapes, sizes, areas, etc. of the figures may be exaggerated for clarity. In addition, although only a portion of the constituent elements are listed for ease of description, the remaining portions should be easily understood by those skilled in the art. Furthermore, those skilled in the art will also understand that various changes in form and details may be made without departing from the scope of the invention as defined by the present invention.

As used herein, "substituted" means that at least one hydrogen atom on a functional group described herein is replaced by a halogen atom (F, Cl, Br or I), a hydroxyl group, a nitro group, an imino group (=NH, =NR, wherein R is a C1-C10 alkyl group), an amidino group, a hydrazine or a hydrazine group, a carboxyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C3-C30 heteroaryl group, or a substituted or unsubstituted C2-C30 heterocycloalkyl group, etc., unless otherwise specified.

As used herein, "(meth)acryl" refers to acryl and/or methacryl.

As used herein, the particle size of an amphoteric anisotropic powder is measured as the maximum length, i.e., the longest length of the powder particles. As used herein, a particle size range of an amphoteric anisotropic powder means that at least 95% of the amphoteric anisotropic powder present in the composition falls within the corresponding range.

As used herein, the average particle size of the emulsified particles refers to the average diameter of each particle. As used herein, the average particle size range of the emulsified particles refers to the range within which at least 95% of the emulsified particles in the composition fall.

In one aspect, a chemically anisotropic powder with improved dispersibility is provided, comprising first polymer spheres and second polymer spheres, wherein the first and second polymer spheres are bonded to each other in a structure in which one polymer sphere at least partially penetrates the other polymer sphere; the first polymer sphere has a core-shell structure; its shell has functional groups; and at least one of the first polymer sphere and the second polymer sphere is negatively or positively charged.

As used herein, a sphere refers to a single body formed from a polymer, for example, having a spherical or ellipsoidal shape, and having a major axis length in the micrometer or nanometer range depending on the maximum length of the main body portion.

According to one embodiment, at least one of the first polymer sphere and the second polymer sphere comprises an ionic vinyl polymer. The ionic vinyl polymer imparts a positive or negative charge to the chemically anisotropic powder, electrostatically preventing particle aggregation (coagulation). In this manner, when the chemically anisotropic powder is used in a composition, it is possible to reduce the amount of thickener used and prevent particle aggregation, thereby providing a stable emulsion composition.

According to another embodiment, the ionic vinyl polymer may be a sodium 4-vinylbenzenesulfonate polymer.

According to another embodiment, the core of the second polymer sphere and the first polymer sphere may include a vinyl polymer, and the shell of the first polymer sphere may include a copolymer of a vinyl polymer having a functional group.

According to yet another embodiment, the vinyl polymer may include a vinyl aromatic polymer, in particular polystyrene.

According to yet another embodiment, the functional group may be siloxane.

According to yet another embodiment, the amphoteric anisotropic powder may have a symmetrical shape, an asymmetrical snowman shape, or an asymmetrical reverse snowman shape depending on where the first polymer sphere and the second polymer sphere are bonded to each other.

According to another embodiment, the amphoteric anisotropic powder may have a particle size of 100-1500 nanometers. In a variation, the amphoteric anisotropic powder may have a particle size of 100-500 nanometers, or 200-300 nanometers. Here, the particle size refers to the maximum length of the amphoteric powder. Specifically, the amphoteric powder can have a particle size of at least 100 nm, at least 200 nm, at least 300 nm, at least 400 nm, at least 500 nm, at least 600 nm, at least 700 nm, at least 800 nm, at least 900 nm, at least 1000 nm, at least 1100 nm, at least 1200 nm, at least 1300 nm or at least 1400 nm, at most 1500 nm, at most 1400 nm, at most 1300 nm, at most 1200 nm, at most 1100 nm, at most 1000 nm, at most 900 nm, at most 800 nm, at most 700 nm, at most 600 nm, at most 500 nm, at most 400 nm, at most 300 nm or at most 200 nm.

In another general aspect, a cosmetic composition comprising a chemically anisotropic powder having improved dispersibility is provided.

According to one embodiment, the chemically anisotropic powder can form micron emulsion particles having a size of 5-200 microns. In one variation, the chemically anisotropic powder can form micron emulsion particles having a size of 10-100 microns, 10-50 microns, or 25 microns. Specifically, the chemically anisotropic powder can form emulsion particles having a size of at least 5 microns, at least 10 microns, at least 15 microns, at least 20 microns, at least 25 microns, at least 30 microns, at least 40 microns, at least 50 microns, at least 80 microns, at least 100 microns, at least 130 microns, at least 150 microns, or at least 180 microns, at most 200 microns, at most 180 microns, at most 150 microns, at most 130 microns, at most 100 microns, at most 80 microns, at most 50 microns, at most 40 microns, at most 30 microns, at most 25 microns, at most 20 microns, at most 15 microns, or at most 10 microns.

Chemically anisotropic powders exhibit varying orientations at interfaces, allowing for the formation of stable micronized emulsion particles. Furthermore, cosmetic compositions containing chemically anisotropic powders offer a unique dual feel, providing both a moisturizing sensation from the large emulsion particles and a comfortable, nourishing sensation from the smaller emulsion particles. Furthermore, the increased repulsive forces between chemically anisotropic powder particles reduce the viscosity of the large emulsion particles, allowing them to disperse, thus forming low-viscosity oil-in-water (O/W) emulsions.

Using conventional molecular-scale surfactants to form stable microemulsified particles with a particle size of tens of microns is difficult. In this case, such surfactants form an interfacial film with a thickness of only a few nanometers. However, when using the chemically anisotropic powders disclosed herein, the thickness of the interfacial film increases to approximately hundreds of nanometers, and a stable interfacial film is formed due to the strong bonds between the powder particles. This method can potentially improve the stability of the emulsion.

According to one embodiment, the amount of the chemically anisotropic powder may be 0.1-15% by weight of the total weight of the cosmetic composition. In one variation, the amount of the chemically anisotropic powder may be 0.5-5% by weight of the total weight of the cosmetic composition. Specifically, the amount of the chemically anisotropic powder is at least 0.1% by weight, at least 0.5% by weight, at least 1% by weight, at least 2% by weight, at least 4% by weight, at least 6% by weight, at least 8% by weight, at least 10% by weight, or at least 12% by weight, and up to 15% by weight, up to 12% by weight, up to 10% by weight, up to 8% by weight, up to 6% by weight, up to 4% by weight, up to 2% by weight, up to 1% by weight, or up to 0.5% by weight, depending on the total weight of the cosmetic composition. The size of the emulsified particles can be controlled to range from a few microns to tens or hundreds of microns by adjusting the content of the chemically anisotropic powder.

According to another embodiment, the cosmetic composition may be an emulsion composition. Specifically, the emulsion may be at least one of the following formulations: water-in-oil (O/W), oil-in-water (W/O), water-in-oil-in-water (W/O/W), or oil-in-water-in-oil (O/W/O).

According to another embodiment, the emulsion may be a water-in-oil (O/W) formulation containing a chemically anisotropic powder, with the oil phase and the water phase being in a weight ratio of 0.1-15:5-60:10-80. In one variation, the emulsion may be a water-in-oil (O/W) formulation containing a chemically anisotropic powder, with the oil phase and the water phase being in a weight ratio of 0.1-5:15-40:50-80. In another variation, the emulsion may be an oil-in-water (W/O) formulation containing a chemically anisotropic powder, with the oil phase and the water phase being in a weight ratio of 1-15:50-80:10-30. The oil phase may include at least one component selected from the group consisting of liquid oils and fats, solid oils and fats, waxes, hydrocarbon oils, higher fatty acids, higher alcohols, synthetic ester oils, and silicone oils.

According to another embodiment, the chemically anisotropic powder may be added to the aqueous phase to provide a cosmetic composition.

According to yet another embodiment, the cosmetic composition may contain at least 15% by weight, at least 16% by weight, at least 17% by weight, at least 18% by weight, at least 19% by weight, or at least 20% by weight, and up to 30% by weight, up to 29% by weight, up to 28% by weight, up to 27% by weight, up to 26% by weight, or up to 25% by weight, based on the total weight of the cosmetic composition. For example, the oil may be present in an amount of 15-30% by weight, 15-25% by weight, or 20-25% by weight. The cosmetic composition having an oil content within the above-defined range not only provides stable micronized emulsified particles but also exhibits improved particle dispersibility, thereby reducing the amount of thickener used.

The oil may be an ester oil, a hydrocarbon oil, paraffin, an animal oil, a vegetable oil, a silicone oil or a combination thereof. Specifically, the oil may be at least one selected from the group consisting of hexyl laurate, dicaprylyl carbonate, diisostearyl malate, butylene glycol dicaprylate/dicaprate, cetyl ethylhexanoate, triethylhexanoin, dicetearyl dimer dilinoleate, caprylic/capric triglyceride, polyglyceryl-2 triisostearate, and pentaerythrytol tetraisostearate; and the hydrocarbon oil may be selected from the group consisting of polybutene, hydrogenated polyisobutene, polyisobutene) and plant-based squalane; while silicone oil is selected from phenyl trimethicone and phenyl dimethicone.

According to yet another embodiment, the cosmetic composition can have a low viscosity emulsion formulation that is essentially non-sticky and has undetectable viscosity. As used herein, "non-sticky" means that its viscosity is so low that it cannot be measured using a conventional viscometer.

In conventional emulsion systems, due to the small size of the emulsion particles, an excessive amount of surfactant must be added as the oil content increases. In such cases, thickeners or viscosity-enhancing materials, such as waxes, are also required to prevent emulsified particle aggregation and phase separation and stabilize the emulsion. This results in negative user experiences, such as a sticky and stiff feel, resembling lotion- or cream-like formulations. In such cases, it is impossible to create emollient-like formulations. In contrast, the chemically anisotropic powders disclosed herein have improved dispersibility, enabling the creation of stable emulsion cosmetic compositions with viscosities below 300 centipoise and emollient-like formulations, even with minimal thickeners, even when the oil content is increased to as much as 25% by weight.

According to yet another embodiment, the cosmetic composition may have a viscosity of at most 300 centipoise. For example, the viscosity may be at most 300 centipoise, at most 290 centipoise, at most 280 centipoise, at most 270 centipoise, at most 260 centipoise, at most 250 centipoise, at most 240 centipoise, at most 230 centipoise, at most 220 centipoise, at most 210 centipoise, at most 200 centipoise, at most 190 centipoise, at most 180 centipoise, at most 170 centipoise, at most 160 centipoise, at most 150 centipoise, at most 140 centipoise, at most 130 centipoise, at most 120 centipoise, at most 110 centipoise, at most 100 centipoise, at most 90 centipoise, at most The viscosity ranges are for illustrative purposes only, and the cosmetic composition may be a non-stick formulation with no detectable viscosity.

The cosmetic composition containing the chemically anisotropic powder exhibits increased repulsive force between emulsified particles and can therefore be dispersed at minimal viscosity. Therefore, it is possible to provide a low-viscosity water-in-oil (O/W) emulsion like a skin softener formulation.

In another aspect, a method for preparing a chemically anisotropic powder is provided, comprising: (1) stirring a first monomer and a polymerization initiator to form a core of a first polymer sphere; (2) stirring the formed core of the first monomer together with the first monomer, the polymerization initiator, and a monomer containing a functional group to form a first polymer sphere having a core-shell structure; and (3) stirring the formed first polymer sphere having a core-shell structure with a second monomer and a polymerization initiator to obtain an anisotropic powder, wherein second polymer spheres are formed.

According to one embodiment, in at least one of steps (1) and (2), an ionic vinyl monomer is mixed with a polymerization initiator and stirred so that at least one of the first polymer sphere and the second polymer sphere has a negative charge or a positive charge.

In steps (1), (2), and (3), the stirring may be rotary stirring. In order to produce uniform particles, homogeneous mechanical mixing and chemical modification are required, and rotary stirring is preferred. Rotary stirring can be performed in a cylindrical reactor, but is not limited thereto.

Here, the internal design of the reactor significantly influences the powder formation. The size and position of the baffles of the cylindrical reactor, as well as the distance from the impeller, have a significant impact on the uniformity of particle formation. Preferably, the spacing between the internal blades and the impeller blades is minimized to make the convection and its intensity uniform, and the powdered reaction mixture is introduced below the level of the blade length while the impeller is maintained at a high rotation speed. The rotation speed can be 200 rpm or higher, and the diameter to reactor height ratio can be 1-3:1-5. Specifically, the reactor can have a diameter of 10-30 cm and a height of 10-50 cm. The reactor size can vary proportionally according to the reaction capacity. In addition, the cylindrical reactor can be made of ceramic, glass or the like. Stirring is preferably carried out at a temperature of 50-90°C.

Simple mixing in a cylindrical rotating reactor produces uniform particles with low energy consumption and maximized reaction efficiency, making it suitable for large-scale production. Conventional tumbling methods, which involve rotating the reactor itself, causing the entire reactor to tilt at a certain angle and rotate at high speed, require high energy consumption and limit reactor size. Due to the limited size of the reactor, production is also limited to small quantities of approximately tens of milligrams or a few grams. Therefore, conventional tumbling methods are not suitable for large-scale production.

According to an embodiment, the first monomer and the second monomer may be the same or different, and specifically may be vinyl monomers. In addition, the first monomer added in step (2) is the same as the first monomer used in step (1), and the initiator used in each step may be the same or different.

According to another embodiment, the vinyl monomer may be a vinyl aromatic monomer. The vinyl aromatic monomer may be a substituted or unsubstituted styrene, for example, at least one selected from styrene, α-methylstyrene, α-ethylstyrene, and para-methylstyrene.

According to another embodiment, the polymerization initiator can be a free radical polymerization initiator. Specifically, the polymerization initiator can be at least one selected from a peroxide and an azo initiator. In addition, ammonium persulfate, sodium persulfate or potassium persulfate can be used. The peroxide free radical polymerization initiator can be at least one selected from the following: benzoyl peroxide, lauryl peroxide, cumene hydroperoxide, methylethyl ketone peroxide, t-butyl hydroperoxide, o-chlorobenzoyl peroxide, o-methoxybenzoyl peroxide, t-butylperoxy-2-ethylhexanoate and t-butylperoxy isobutyrate. The azo-based free radical polymerization initiator may be at least one selected from 2,2-azobisisobutyronitrile, 2,2'-azobis(2-methylisobutyronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile).

According to another embodiment, in step (1), the first monomer and the polymerization initiator may be mixed at a weight ratio of 100-250:1.

Specific examples of the ionic vinyl monomer are the same as those mentioned above. It is possible to increase the uniformity of the anisotropic powder within the above weight ratio.

In one variation, in step (1), the ionic vinyl monomer can be added simultaneously to the first monomer and the polymerization initiator. Thus, the first monomer, the polymerization initiator, and the ionic vinyl monomer can be mixed in a weight ratio of 100-250:1:0.001-5. The size and shape of the powder can be determined by controlling the size of the first polymer spheres in step (1), and the size of the first polymer spheres can also be controlled by the ratio of the first monomer, the initiator, and the ionic vinyl monomer. Furthermore, it is possible to improve the uniformity of the anisotropic powder by mixing the first monomer, the polymerization initiator, and the ionic vinyl monomer within the above-defined ratios.

According to one embodiment, the ionic vinyl monomer may be sodium 4-vinylbenzenesulfonate. The anisotropic powder obtained by using the ionic vinyl monomer contains an ionic vinyl polymer, thereby preventing particle swelling and imparting positive or negative charges on the powder surface, thereby preventing electrostatic aggregation (coagulation) of the particles.

When the size of the chemically anisotropic powder is 200-250 nanometers, it can be derived from first polymer spheres, which are prepared by reacting a first monomer with an initiator and an ionic vinyl monomer in a ratio of 110-130:1:2-4. The ratio is particularly preferably 115-125:1:2-4, and more particularly 120:1:3.

In addition, when the size of the chemically anisotropic powder is 400-450 nanometers, it can be derived from first polymer spheres obtained by reacting a first monomer, an initiator, and an ionic vinyl monomer in a ratio of 225-240:1:1-3, specifically 230-235:1:1-3, and more specifically 235:1:2.

Furthermore, when the size of the chemically anisotropic powder is 1100-1500 nm, it can be derived from first polymer spheres obtained by reacting a first monomer, an initiator, and an ionic vinyl monomer in a ratio of 110-130:1:0, specifically 115-125:1:0, and more specifically 120:1:0.

In addition, the chemically anisotropic powder having an asymmetric snowman shape can be derived from a first polymer sphere obtained by reacting a first monomer, an initiator, and an ionic vinyl monomer in a ratio of 100-140:1:8-12, specifically 110-130:1:9-11, and more specifically 120:1:10.

Furthermore, the chemically anisotropic powder having an asymmetric inverse snowman shape can be derived from a first polymer sphere obtained by reacting a first monomer, an initiator, and an ionic vinyl monomer in a ratio of 100-140:1:1-5, specifically 110-130:1:2-4, and more specifically 120:1:3.

According to another embodiment, in step (2), the monomer including the first monomer, the polymerization initiator and the monomer containing the functional group can be mixed at a weight ratio of 80-98:0.2-0.8:2-20. In a variation, the first monomer, the polymerization initiator and the monomer containing the functional group can be mixed at a weight ratio of 160-200:1:6-40. It is possible to control the coating degree according to the ratio of the reactants, and the coating degree determines the shape of the chemically anisotropic powder. When the first monomer, the polymerization initiator and the monomer containing the functional group are mixed using the above-defined ratio, the coating thickness increases by about 10-30%, specifically about 20%, compared to the original thickness. In this case, the powder formation can proceed smoothly without the following problems, such as failure of powder formation due to excessively thick coating or multi-directional powder formation due to excessively thin coating. In addition, it is possible to improve the uniformity of the anisotropic powder within the above-mentioned weight ratio.

According to another embodiment, the functional group-containing monomer can be a siloxane-containing compound. Specifically, it can be a siloxane-containing (meth)acrylate monomer, and in particular, it can be at least one selected from the group consisting of 3-(trimethoxysilyl)propyl acrylate, 3-(trimethoxysilyl)propyl methacrylate, vinyltriethoxysilane, and vinyltrimethoxysilane.

According to another embodiment, in step (3), the second monomer and the polymerization initiator may be mixed in a weight ratio of 200-250:1.

In one variation, in step (3), the ionic vinyl monomer may be added to the second monomer and the polymerization initiator. Thus, the second monomer, the polymerization initiator, and the ionic vinyl monomer may be mixed in a weight ratio of 200-250:1:0.001-5. Specific examples of the ionic vinyl monomer are the same as those described above. Within the above weight ratio, it may be possible to increase the uniformity of the anisotropic powder.

According to another embodiment, in step (3), the second monomer can be mixed with 100 parts of the first polymer spheres in an amount of 40-300 parts by weight. Specifically, when the content of the second monomer is 40-100 weight % of the first polymer spheres, an asymmetric snowman-shaped powder is obtained. When the content of the second monomer is 100-150 weight % or 110-150 weight % of the first polymer spheres, a symmetrical powder is obtained. In addition, when the content of the second monomer is 150-300 weight % or 160-300 weight % of the first polymer spheres, an asymmetric reverse snowman-shaped powder is obtained. It is possible to increase the uniformity of the anisotropic powder within the above weight ratios.

According to the related art, in order to increase the surface activity of Pickering spherical powder particles, many attempts have been made to impart amphoteric surface activity thereto. This can be illustrated by Janus spherical particles. However, such particles are subject to geometric limitations and have problems with uniform large-scale production, and therefore cannot be practically applied. In contrast, the method for preparing the amphoteric anisotropic powder disclosed herein does not use a cross-linking agent, and therefore does not cause agglomeration, and provides high yield and uniformity. In addition, the method disclosed herein uses a simple stirring process, which is more suitable for mass production than a tumbling process. Specifically, the method disclosed herein has the advantage that it allows nano-sized particles with a size of 300 nanometers or less to be mass-produced in quantities of tens of grams and tens of kilograms.

The present invention will now be described more fully hereinafter with reference to exemplary embodiments illustrated in the accompanying drawings. However, the present invention may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein.

Preparation Example 1. Preparation of polystyrene (PS) first polymer spheres

Styrene as a monomer, sodium 4-vinylbenzenesulfonate as an ionic vinyl monomer, and azobisisobutyronitrile (AIBN) as an initiator were mixed in an aqueous phase and reacted at 75°C for 8 hours. The reaction was carried out in a glass cylindrical reactor with a diameter of 11 cm and a height of 17 cm, with the reaction mixture stirred at 200 rpm.

Preparation Example 2. Preparation of coated first polymer spheres having a core-shell (CS) structure

The polystyrene (PS) first polymer spherical particles obtained above were mixed with styrene as a monomer and 3-(trimethoxysilyl)propyl acrylate (TMSPA) and azobisisobutyronitrile (AIBN) as initiators to react. The reaction was carried out by stirring the reaction mixture in a cylindrical reactor.

Preparation Example 3. Preparation of ionized anisotropic powder

The polystyrene core-shell aqueous dispersion (PC-CS) obtained above was mixed with styrene as a monomer, sodium 4-vinylbenzenesulfonate as an ionic vinyl monomer, and azobisisobutyronitrile (AIBN) as an initiator, and the reaction mixture was heated to 75°C to react. The reaction was carried out by stirring the reaction mixture in a cylindrical reactor.

Example 1. Low-viscosity emulsion cosmetic composition with high oil content

The emulsion cosmetic composition was prepared according to the composition listed in Table 1 below. The oil phase was heated to dissolve, while the aqueous phase containing the anisotropic powder was also heated to the same temperature. The oil phase was then gradually added to the aqueous phase, emulsifying at a low speed. A thickener was then added and stirred to obtain a low-viscosity, high-oil-content, water-in-oil emulsion cosmetic composition.

[Table 1]

Ingredients Quantity (weight %) Oil (Hydrogenated Polydecene) 15.00 Butter (Shea Butter) 2.00 Water (deionized water) 68.55 Metal ion chelating agent (EDTA 2Na) 0.05 Moisturizer (Butylene Glycol) 7.00 Moisturizer (glycerin) 5.00 Anisotropic powder 1.85 Preservative (Phenoxyethanol) 0.40 Preservative (Ethylhexylglycerin) 0.05 spices 0.1

Test Example 1. Viscosity Comparison

0.2 ml of each of the cosmetic composition of Example 1, a conventional skin softening formulation, and a conventional emulsion formulation was dropped onto a cardboard sheet, which was then tilted at a 60° angle. As shown in Figure 2, the cosmetic composition of Example 1, like the conventional skin softening formulation, exhibited high fluidity, excellent spreadability, and a pleasant feel during use.

Test Example 2. Preparation stability test

The cosmetic composition obtained in Example 1 was placed at (a) room temperature, (b) 45°C, (c) 60°C, and (d) maintained at a constant temperature under cooling. The cosmetic composition was then observed for 10 weeks to determine whether demulsification occurred. As can be seen in Figure 4 , the cosmetic composition maintained its formulation stably without demulsification.

Test Example 3. Evaluation of User Experience

Forty female subjects aged between 30 and 40 used the cosmetic composition obtained in Example 1. They then completed a questionnaire survey (15-point scale, with 1: very low and 10: very high) to evaluate their experience. The cosmetic composition obtained in Example 1 was compared with a conventional skin softening formulation, a conventional lotion, and a conventional cream.

[Table 2]

Moisturizing effect Water supply Moisturizing effect Example 1 8 9 8 Traditional skin softening preparations 8 8 2 Traditional Soft Lotion 5 4 6 Traditional cream 4 2 8

The results show that the emulsified particles of the cosmetic composition obtained from Example 1 coexist without aggregation, and the cosmetic composition provides a unique dual experience, including the moisturizing effect from the large emulsified particles and the comfortable moisturizing effect from the smaller emulsified particles.

Test Example 4. Evaluation of Moisturizing Effect and Skin Glossiness

The cosmetic composition obtained in Example 1, a conventional softener, a conventional lotion, and a conventional cream were applied to the skin of 15 researchers from the company. The moisturizing effect and skin glossiness of each sample were then measured. Moisturizing effect was assessed by measuring skin moisture content before, four hours after, and seven hours after application of each sample under constant temperature and humidity conditions (24°C, 40% relative humidity). Skin glossiness was assessed by measuring skin gloss before and after application of each sample. After cleansing, the skin was kept under constant temperature and humidity for 15 minutes, and then the glossiness of each subject's forearm was measured. Skin moisture content was determined by measuring skin capacitance using a skin moisture measurement system (Corneometer CM825, C+K Electronic Co., Germany); the results are shown in Figure 5. Skin glossiness was measured by measuring the pattern of light reflected back from the instrument after irradiation with light of a specific wavelength; the results are shown in Figure 6.

As can be seen from Figures 5 and 6, the cosmetic composition obtained in Example 1 exhibits moisturizing effect and skin glossiness like lotion or cream, and has similar skin softening properties.

Although exemplary embodiments have been shown and described, various modifications in form and detail may be made to the embodiments without departing from the spirit of the invention and the scope of the appended claims. Therefore, it is intended that the scope of the present invention encompass all embodiments that fall within the spirit and scope of the appended claims.

【Explanation of symbols】

none

Claims (6)

1. A cosmetic composition comprising: A chemically anisotropic powder with improved dispersibility, comprising first polymer spheres and second polymer spheres. The first polymer sphere and the second polymer sphere are bonded to each other in a structure in which one polymer sphere is at least partially infiltrated into the other polymer sphere; The first polymer sphere has a core-shell structure; The shell has a functional group, which is a siloxane; At least one of the first polymer sphere and the second polymer sphere is negatively or positively charged; Wherein, at least one of the first polymer sphere and the second polymer sphere comprises an ionic vinyl polymer; and Wherein, the cores of the second polymer sphere and the first polymer sphere comprise a vinyl polymer, including polystyrene, and the shell of the first polymer sphere comprises a copolymer of vinyl monomers having functional groups. The oil includes at least one selected from the following: ester oils selected from hexyl laurate, dioctyl carbonate, diisostearyl malate, cetyl ethylhexanoate, triisooctyl glycerol, dicetearyl dimelanoate, polyglycerol-2-triisostearyl, and pentaerythritol tetraisostearyl; and hydrocarbon oils selected from polybutene, vegetable squalane, and hydrogenated polydecene. Wherein, based on the total weight of the cosmetic composition, the oil content is 15-30% by weight, and The cosmetic composition is a low-viscosity emulsion formulation with a viscosity of 300 centipoise or less. 2. The cosmetic composition according to claim 1, wherein the ionic vinyl polymer is a sodium 4-vinylbenzenesulfonate polymer. 3. The cosmetic composition according to claim 1, characterized in that, depending on the location where the first polymer sphere and the second polymer sphere are bonded to each other, the chemically anisotropic powder has a symmetrical shape, an asymmetrical snowman shape, or an asymmetrical reverse snowman shape. 4. The cosmetic composition according to claim 1, characterized in that its particle size is 100-1500 nanometers. 5. The cosmetic composition according to claim 1, wherein the chemically anisotropic powder forms micron-sized emulsion particles with a size of 5-200 micrometers. 6. The cosmetic composition according to claim 1, wherein the chemically anisotropic powder is present at 0.1 to 15% by weight of the total weight of the cosmetic composition.