A pickering emulsion based on pearl powder stabilization and a method of making the same

Abstract

The present application provides a Pickering emulsion based on pearl powder stability. Specifically, the present application provides a Pickering emulsion based on pearl powder stability, the emulsion comprises: pearl powder as emulsifier, oil, water; wherein the particle size of the pearl powder is in the range of 100 nm to 800 nm. The present application uses non-toxic, non-irritating, renewable, and high efficacy pearl powder as emulsifier, reduces the burden on the skin caused by traditional surfactant emulsifier, and the product is more mild; the pearl powder can be stably suspended at the oil-water interface, the stability of the Pickering emulsion formed is high, and many oil-water systems that are difficult to stabilize by ordinary emulsifiers can be stably stabilized; the Pickering emulsion of the present application is suitable for various oil-water systems, widens the application range of Pickering emulsion, and has very high application value in the field of cosmetics.

Description

Technical Field

[0001] This invention belongs to the field of cosmetic technology, specifically relating to a pearl powder-stabilized Pickering emulsion and its preparation method. Background Technology

[0002] An emulsion is a liquid-phase dispersion system in which one phase is dispersed in the form of extremely small droplets within another phase, and it has important applications in daily life. Due to its high oil / water interfacial area, an emulsion is a thermodynamically unstable system, thus requiring the addition of emulsifiers to stabilize it. Traditional emulsifiers are mainly surfactants, but when present in cosmetic emulsion systems, they only stabilize the oil-water interface, offering no skincare benefits and potentially causing contact dermatitis, dermatitis, and allergic reactions.

[0003] Pickering emulsions are a novel type of emulsion system where solid particles replace traditional surfactants for stabilization. Compared to emulsions stabilized by traditional surfactants, solid particles demonstrate more positive performance as emulsifiers in cosmetics. Using solid particles as emulsifiers in cosmetics not only maintains the long-term thermodynamic stability of the emulsion system but also reduces the skin irritation caused by the inherent properties of surfactants.

[0004] Currently, existing solid particles used as emulsifiers in cosmetics include inorganic particles such as titanium dioxide and zinc oxide. While titanium dioxide and zinc oxide, when used as pickering emulsifiers, offer some coverage and sun protection, the particles themselves do not provide skincare benefits and may cause photosensitivity. Compared to inorganic particles, biologically derived solid particles offer advantages such as broader selectivity, higher safety, and inherent biological activity and skincare benefits.

[0005] Pearl powder is a natural organic-inorganic composite granule that has been widely used in traditional Chinese medicine, cosmetics, and health products since ancient times due to its non-toxic, non-irritating, and highly effective properties. Highly effective pearl powder has great potential in the preparation of Pickering emulsions; however, there are currently no reports of pearl powder being used as a solid particulate emulsifier in cosmetics.

[0006] There are many products on the market that use pearl powder or its extracts as active ingredients. Most of these products add pearl powder directly to the emulsion. However, pearl powder has low solubility and a high surface size effect. As solid particles in the system, it is easily precipitated by gravity, which can disrupt the stability of the original emulsion and limit its addition amount, thus hindering the realization of efficacy. If pearl powder extracts are used as active ingredients in the product, it is difficult to demonstrate the efficacy of the contained active ingredients.

[0007] In summary, there is an urgent need in this field for research on stable, widely applicable, and low-irritant Pickering emulsions using pearl powder as an emulsifier. Summary of the Invention

[0008] The purpose of this invention is to provide a stable, widely applicable, and low-irritation Pickering emulsion using pearl powder as an emulsifier.

[0009] In a first aspect of the invention, a pearl powder-stabilized Pickering emulsion is provided, the emulsion comprising: pearl powder as an emulsifier, oil, and water;

[0010] The pearl powder has a particle size in the range of 100 nanometers to 800 nanometers.

[0011] In another preferred embodiment, the pearl powder has a particle size in the range of 200 nanometers to 700 nanometers.

[0012] In another preferred embodiment, the pearl powder has a particle size in the range of 300 nanometers to 600 nanometers.

[0013] In another preferred embodiment, the microstructure of the pearl powder is a regular spherical shape.

[0014] In another preferred embodiment, the size of the emulsified particles of the Pickering emulsion is in the range of 50 micrometers to 300 micrometers.

[0015] In another preferred embodiment, the Pickering emulsion contains more than 90% emulsified particles with a particle size of 80 to 120 micrometers.

[0016] In another preferred embodiment, the pearl powder has a mass concentration of 0.2% to 4%.

[0017] In another preferred embodiment, the pearl powder has a mass concentration of 0.3% to 3.5%.

[0018] In another preferred embodiment, the pearl powder has a mass concentration of 0.4% to 3%.

[0019] In another preferred embodiment, the oil concentration in the Pickering emulsion is 20% to 90% by mass.

[0020] In another preferred embodiment, the oil concentration in the Pickering emulsion is 40% to 70% by mass.

[0021] In another preferred embodiment, the oil concentration in the Pickering emulsion is 50%.

[0022] In another preferred embodiment, the oils in the Pickering emulsion are selected from the group consisting of alkane oils, ester oils, natural oils, or combinations thereof.

[0023] In another preferred embodiment, the alkane oils include straight-chain alkanes and branched-chain alkanes, selected from the group consisting of different types of mineral oil, isohexadecane, isooctane, isooctane, isododecane, isohexadecane, isoeicosane, C 10 -C 13 Isoalkanes, C 12 -C 14 Isoalkanes, C 12 -C 20 Isoalkanes, used to synthesize squalane, sucrose squalane, plant-derived squalane, squalane, or combinations thereof.

[0024] In another preferred embodiment, the ester oil is selected from the group consisting of: ethylhexyl palmitate, isopropyl palmitate, isopropyl myristate, isopropyl palmitate, triethylhexanoate, pentaerythritol tetraethylhexyl ester, ethyl stearate, butyl stearate, ethyl oleate, ethyl linoleate, isopropyl linoleate, or combinations thereof.

[0025] In another preferred embodiment, the natural oil is selected from the group consisting of: olive oil, castor oil, peanut oil, palm oil, palm kernel oil, coconut oil, sunflower seed oil, sesame oil, soybean oil, safflower oil, almond oil, avocado oil, evening primrose oil, rice bran oil, macadamia seed oil, wheat germ oil, argan kernel oil, kukui nut oil, rice germ oil, almond oil, olive fruit oil, sesame oil, corn germ oil, rapeseed oil, peach kernel oil, safflower oil, grape seed oil, peony seed oil, sunflower seed oil, flaxseed oil, mango oil, meadowfoam seed oil, jojoba seed oil, cocoa seed oil, rosehip oil, or combinations thereof.

[0026] In another preferred embodiment, the Pickering emulsion may contain glycerin, xanthan gum, or a combination thereof.

[0027] In another preferred embodiment, the glycerol concentration in the Pickering emulsion is 0% to 5% by mass.

[0028] In another preferred embodiment, the xanthan gum concentration in the Pickering emulsion is 0% to 1%.

[0029] In another preferred embodiment, the Pickering emulsion comprises:

[0030]

[0031] In a second aspect of the present invention, a method for preparing a pearl powder-stabilized Pickering emulsion is provided, comprising the following steps:

[0032] (a) Provide the pearl powder according to the first aspect of the present invention, which is added to water as phase A and oil as phase B;

[0033] (b) Phase A and Phase B are mixed and homogenized to obtain Pickering emulsion.

[0034] In another preferred embodiment, in step (a), phase A and phase B need to be preheated.

[0035] In another preferred embodiment, in step (a), the preheating temperature of phase A and phase B is 20-90°C.

[0036] In another preferred embodiment, in step (a), phase A comprises glycerol and / or xanthan gum.

[0037] In another preferred embodiment, the step further includes:

[0038] (c) Stir and cool the Pickering emulsion obtained in step (b) to 40-45°C, add other ingredients, continue stirring and cooling to room temperature, and then package to obtain the final product.

[0039] In another preferred embodiment, in step (c), other ingredients include fragrances, preservatives, antioxidants, aromatics, or combinations thereof.

[0040] In another preferred embodiment, the mixing method is selected from the group consisting of: stirring at 500 r / min to 5000 r / min for 5 min to 30 min, homogenizing at 3000 r / min to 20000 r / min for 1 min to 15 min, and ultrasonic treatment at 10% to 50% power for 5 min to 30 min; preferably, the mixing method is ultrasonic treatment at 10% to 50% power for 5 min to 30 min.

[0041] In another preferred embodiment, the rotational speed for homogenization in step (c) is 3000 r / min to 20000 r / min, preferably 6000 r / min to 15000 r / min.

[0042] In another preferred embodiment, the homogenization time in step (c) is 1 min to 15 min, preferably 2 min to 8 min.

[0043] In another preferred embodiment, the pearl powder of the present invention is pretreated pearl powder, wherein the pretreatment step includes:

[0044] (a) Provide raw pearl powder, add it to a solvent, and prepare a suspension of raw pearl powder;

[0045] (b) The suspension of the original pearl powder from step (a) is mechanically ball-milled and dried to obtain the pearl powder described in the first aspect of the present invention.

[0046] In another preferred embodiment, the size of the raw pearl powder exceeds 1000 nanometers.

[0047] In another preferred embodiment, the size of the raw pearl powder is in the range of 2000 to 3000 nanometers.

[0048] In another preferred embodiment, the raw pearl powder undergoes a pretreatment process of drying at 50°C to 90°C until the moisture content is less than 5%.

[0049] In another preferred embodiment, in step (a), the solvent is anhydrous ethanol aqueous solution.

[0050] In another preferred embodiment, in step (a), the concentration of the anhydrous ethanol aqueous solution is 10 wt% to 100 wt%, preferably 50% to 100 wt%.

[0051] In another preferred embodiment, in step (a), the concentration of the suspension of the raw pearl powder is 5 wt% to 20 wt%.

[0052] In another preferred embodiment, in step (b), the grinding cylinder of the ball mill for the mechanical ball mill contains zirconia grinding balls with a diameter of 0.3 mm.

[0053] In another preferred embodiment, in step (b), the mass ratio of the grinding ball to the pearl powder suspension is 2:8 to 8:2, preferably 4:6 to 6:4.

[0054] In another preferred embodiment, in step (b), the drying conditions are 60–100°C for 18–30 h, preferably 24 h.

[0055] In another preferred embodiment, in step (b), the grinding conditions of the mechanical ball mill are a rotation speed of 600 r / min to 2500 r / min, a grinding time of 30 min to 360 min, and a temperature of 20 to 60 °C. Preferably, the grinding conditions are a rotation speed of 1000 r / min to 1800 r / min, a grinding time of 60 min to 180 min, and a temperature of 20 °C.

[0056] In a third aspect of the invention, a cosmetic composition is provided comprising the pearl powder-stabilized Pickering emulsion described in the first aspect of the invention.

[0057] In another preferred embodiment, the cosmetic composition comprising a pearl powder-stabilized Pickering emulsion includes: a skin lotion, a skin cream, a sunscreen, or a combination thereof.

[0058] In a fourth aspect of the invention, the use of the pearl powder-stabilized Pickering emulsion described in the first aspect of the invention in the preparation of cosmetic compositions is provided.

[0059] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0060] Figure 1 Scanning electron microscope images of the raw pearl powder in Example 1 and the pretreated pearl powder of the present invention are shown;

[0061] Figure 2 Microscopic images (A) of the stabilized emulsions when the original pearl powder and the pretreated pearl powder of the present invention were used as emulsifiers in Example 2, and a particle size distribution diagram (B) of the emulsion stabilized by the pretreated pearl powder were shown.

[0062] Figure 3 The appearance (A) and microscopic photograph (B) of the Pickering emulsion obtained by using pretreated pearl powder, titanium dioxide and zinc oxide as emulsifiers in Example 3 after standing for 24 hours are shown.

[0063] Figure 4 The image shows a microscope photograph of the pretreated pearl powder of the present invention used as an emulsifier in Example 4, which stabilizes different oil-water systems to form emulsions.

[0064] Figure 5 The image shows a microscope photograph of the emulsion formed by stabilizing the silicone oil / water system in Example 5 using pretreated pearl powder, Tween 80, and Brij 72 / 721 as emulsifiers, after one month of storage.

[0065] Figure 6 Microscopic images of the pretreated pearl powder stabilized squalane / water system forming emulsions according to the present invention under different oil-water volume ratios are shown in Example 6.

[0066] Figure 7 The image shows the chorioallantoic membrane vascular reaction of the pretreated pearl powder stabilized Pickering emulsion (A) and Brij72 / 721 emulsifier stabilized emulsion (B) of the present invention in Example 7. Detailed Implementation

[0067] Through extensive and in-depth research, the inventors have unexpectedly discovered for the first time a Pickering emulsion, which is stabilized by pearl powder and suitable for various oil-water systems.

[0068] Specifically, the inventors used unmodified pearl powder with a size ranging from 100 nanometers to 800 nanometers as a single emulsifier to obtain a highly stable, non-toxic, and non-irritating Pickering emulsion suitable for various oil-water systems. The preparation method of this emulsion is simple and easy to operate; that is, the pearl powder is first pretreated by mechanical ball milling, and then added to the aqueous phase as an emulsifier, followed by direct oil-water mixing and homogenization to prepare a stable emulsion. The Pickering emulsion of this invention can be widely used in cosmetic compositions to enhance product quality and efficacy. This invention was completed based on this.

[0069] The pearl powder-stabilized Pickering emulsion of the present invention not only enables pearl powder to be stably suspended at the oil-water interface in various oil-water systems (including alkane oils, ester oils, natural oils, etc.), but also solves to some extent the environmental and skin irritation problems caused by the large-scale use of surfactants. It has high application value in the cosmetics field.

[0070] Pearl powder

[0071] Pearl powder is a natural organic-inorganic composite granule. It is rich in 18 kinds of amino acids and more than 20 kinds of trace elements such as phosphorus, iron, manganese, selenium, zinc, and copper, as well as various vitamins and a large amount of active calcium (Tsukamoto D, Sarashina I, Endo K. Biochemical and Biophysical Research Communications, 2004, 320(4):1175-1180). Modern research has shown that pearl powder has a variety of effects, including: promoting wound healing (Dai JP, Chen J, Bei YF, et al. Pharmaceutical Biology, 2010, 48(2): 122-127), anti-inflammatory effects (Wang Chaolin, Ning Yaoyu, Cheng Jianping, et al. Journal of Guangxi Medical University, 1994, 11(3): 280-283), anti-osteoporosis (Chen Lianjian, Li Cheng, Li Ting. Chinese Herbal Medicines, 2004, 27(3): 363-365), inhibiting tyrosinase and reducing melanin production (Shao DZ, Wang CK, Hwang HJ, et al. Journal of Cosmetic Science, 2010, 61(2): 133-145). Therefore, it has been widely used in traditional Chinese medicine, cosmetics and health products since ancient times.

[0072] As used herein, the terms "pearl powder of the present invention," "pretreated pearl powder of the present invention," "pearl powder," and "pretreated pearl powder" are used interchangeably and refer to pearl powder that can be used as an emulsifier in Pickering emulsions in the present invention. The pearl powder is pearl powder that has undergone ball milling pretreatment, with a particle size in the range of 100 nanometers to 800 nanometers and a regular spherical microstructure.

[0073] In another preferred embodiment, the pearl powder of the present invention has a particle size in the range of 200 nanometers to 700 nanometers.

[0074] In another preferred embodiment, the pearl powder of the present invention has a particle size in the range of 300 nanometers to 600 nanometers.

[0075] As used herein, the term "raw pearl powder" refers to large-sized pearl powder purchased from commercial sources. The raw pearl powder described herein can be prepared into the pretreated pearl powder of this invention using mechanical ball milling, resulting in a particle size exceeding 1000 nanometers.

[0076] Other ingredients

[0077] In the Pickering emulsion of the present invention, one or more additional ingredients may be added, as long as the additional ingredients do not have a substantial effect on the Pickering emulsion of the present invention (such as causing a decrease in emulsion stability).

[0078] These additional ingredients are optional, and representative additional ingredients include (but are not limited to): preservatives, antioxidants, fragrances, colorants (such as natural colorants), aromatics, or other active ingredients or excipients permitted in cosmetics.

[0079] For example, a preservative can be added to the oily stock solution of the present invention to further improve its long-term storage performance. The preservative is selected from: formaldehyde releasers, hydantoin, isothiazolinones, parabens, and alcohols.

[0080] In another preferred embodiment, the alcohol is selected from: 2-phenoxyethanol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, ethylhexylglycerol, or combinations thereof;

[0081] In another preferred embodiment, the parabens are selected from: methylparaben, ethylparaben, propylparaben, butylparaben, isopropylparaben, and isobutylparaben, or combinations thereof;

[0082] In another preferred embodiment, the formaldehyde releaser is selected from: 1,3-dihydroxymethyl-5,5-dimethylhydantoin (DMDMH), imidazolidinyl urea, diazoimidazolidinyl urea, and sodium hydroxymethylglycinate or combinations thereof.

[0083] In another preferred embodiment, the mass concentration of fragrance in the emulsion is 0.1% to 0.3%.

[0084] In another preferred embodiment, the preservative concentration in the emulsion is 0.01% to 0.5% by mass.

[0085] Pearl powder stabilized Pickering emulsion and cosmetic compositions

[0086] As used herein, "Pickering emulsion" and "Pickering emulsion" are used interchangeably, referring to a novel type of emulsion in which solid particles replace traditional organic surfactants to stabilize the emulsion system. An emulsion is a dispersion system composed of two immiscible liquid phases, where the internal or dispersed phase is dispersed as droplets in the external or continuous phase. Pickering emulsions do not use amphiphilic surfactants to reduce interfacial tension; stable emulsions can be prepared by directly dispersing colloidal particles in the colloidal size range within the emulsion.

[0087] In this invention, the terms "Pickerling emulsion stabilized based on pearl powder," "Pickerling emulsion stabilized based on pretreated pearl powder of this invention," and "Pickerling emulsion of this invention" are used interchangeably. These terms all refer to Pickerling emulsions that stabilize various oil-water systems using pretreated pearl powder of this invention as an emulsifier.

[0088] In another preferred embodiment, the pretreated pearl powder of the present invention refers to small-sized pearl powder (particle size in the range of 100 nanometers to 800 nanometers) after ball milling.

[0089] In another preferred embodiment, the oil of the present invention can be an oil acceptable in the cosmetics field.

[0090] Based on the Pickering emulsion of the present invention, the present invention also provides a cosmetic composition comprising the Pickering emulsion. In addition to the Pickering emulsion of the present invention, the cosmetic composition further comprises a carrier that can be used in cosmetics.

[0091] In another preferred embodiment, the cosmetic composition includes: skin lotion, skin cream, sunscreen, or a combination thereof.

[0092] Preparation method

[0093] The method for preparing the Pickering emulsion of the present invention includes the following steps:

[0094] (a) The pretreated pearl powder of the present invention is added to water as phase A, mixed evenly, and heated to 20°C to 90°C;

[0095] (b) Mix the oil as phase B evenly and heat to 20°C~90°C;

[0096] (c) Mix phase A and phase B evenly, and then homogenize or sonicate at a temperature of 20°C to 90°C to obtain a pearl powder stabilized Pickering emulsion based on the present invention.

[0097] In another preferred embodiment, glycerin and / or xanthan gum may also be added in step (a).

[0098] In another preferred embodiment, in step (b), the pH of the suspension is adjusted to 6 to 10 using a pH buffer solution with a mass fraction of 0.1% to 1%.

[0099] In another preferred embodiment, the step further includes:

[0100] (d) Stir and cool the Pickering emulsion obtained in step (c) to 40-45°C, add other ingredients, continue stirring and cooling to room temperature, and then package to obtain the final product.

[0101] In another preferred embodiment, in step (d), other ingredients include fragrances, preservatives, antioxidants, or combinations thereof.

[0102] In another preferred embodiment, the mixing method in the preparation method is selected from the following group: stirring at 500r / min to 5000r / min for 5min to 30min, homogenizing at 3000r / min to 20000r / min for 1min to 15min, and ultrasonic treatment at 10% to 50% power for 5min to 30min; preferably, the mixing method in the preparation method is ultrasonic treatment at 10% to 50% power for 5min to 30min.

[0103] In another preferred embodiment, the homogenization method in step (c) is to homogenize at 3000 r / min to 20000 r / min for 1 min to 15 min; preferably, the homogenization method in step (c) is to homogenize at 6000 r / min to 15000 r / min for 2 min to 8 min.

[0104] The pearl powder described in this invention also requires pretreatment, including the following steps:

[0105] (a) The raw pearl powder (2000-3000 nm) is dried at 50°C-90°C until the moisture content is less than 5% to obtain dried raw pearl powder.

[0106] (b) The dried raw pearl powder obtained in step (a) is mixed with anhydrous ethanol aqueous solution to prepare a raw pearl powder suspension;

[0107] (c) The suspension obtained in step (b) is placed in a ball mill, wherein the grinding cylinder contains 0.3 mm diameter zirconium oxide grinding balls, and the mass ratio of the grinding balls to the pearl powder suspension is 2:8 to 8:2; the mixture is ground in a grinding mill to obtain a pretreated pearl powder slurry.

[0108] (d) Place the pretreated pearl powder slurry obtained in step (c) in a forced-air drying oven and dry it at 60-100℃ for 18-30 hours. After sieving, the pretreated pearl powder is obtained.

[0109] In another preferred embodiment, in step (b), the concentration of the anhydrous ethanol aqueous solution is 10 wt% to 100 wt%, preferably 50% to 100 wt%.

[0110] In another preferred embodiment, in step (b), the concentration of the original pearl powder suspension is 5 wt% to 50 wt%, preferably 8 wt% to 20 wt%.

[0111] In another preferred embodiment, in step (c), the mass ratio of the grinding balls to the original pearl powder suspension is 4:6 to 6:4.

[0112] In another preferred embodiment, in step (c), the grinding conditions of the ball mill are: a rotation speed of 600 r / min to 2500 r / min, a grinding time of 30 min to 360 min, and a temperature of 20 to 60°C. Preferably, the rotation speed is 1000 r / min to 1800 r / min, the grinding time is 60 min to 180 min, and the temperature is 20°C.

[0113] In another preferred embodiment, in step (d), the drying conditions are 60–100°C for 24 hours.

[0114] The main advantages of this invention include:

[0115] 1) The preparation method of the pearl powder-stabilized Pickering emulsion described in this invention is simple and easy to operate. The pearl powder of this invention does not require any chemical modification and can be obtained by mechanical ball milling pretreatment.

[0116] 2) The Pickering emulsion based on pearl powder stability described in this invention uses non-toxic, non-irritating, renewable, and highly effective pearl powder as a single emulsifier, which reduces the burden on the skin caused by traditional surfactant emulsifiers, making the product gentler.

[0117] 3) The Pickering emulsion based on pearl powder stability described in this invention has high stability and is suitable for various oil-water systems, which broadens the application range of Pickering emulsion and has high application value in the cosmetics field.

[0118] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, percentages and parts are weight percentages and parts by weight.

[0119] Experimental materials and equipment

[0120] Raw pearl powder (particle size between 2000 nanometers and 3000 nanometers), Zhejiang Oushiman Group Co., Ltd.

[0121] Brij 72 / 721, Polyoxyethylene-2(21) stearyl alcohol ether, Croda Chemicals Ltd.;

[0122] Tween 80, Polysorbate-80, Croda Chemicals Co., Ltd.;

[0123] Ball mill, TJX-450 model, Tianjin Dongfang Tianjing Technology Development Co., Ltd.;

[0124] Scanning electron microscope, JSM-7500F, Nippon Electron Ltd.;

[0125] Homogenizer, T80 model, EKK GmbH, Germany;

[0126] Weighing balance, ME204E model, Mettler AG, Switzerland;

[0127] Forced-air drying oven, DHG-9146A, Shanghai Jinghong Experimental Equipment Co., Ltd.;

[0128] Laser particle size analyzer, Mastersizer 3000, Malvern Panaco;

[0129] Example 1. Preparation of the pretreated pearl powder of the present invention

[0130] (1) Raw pearl powder (2000-3000 nm) was dried at 70℃;

[0131] (2) The dried raw pearl powder was mixed with anhydrous ethanol to prepare an 8wt% raw pearl powder suspension, which was placed in a ball mill. The grinding cylinder contained zirconia grinding balls with a diameter of 0.3mm. The mass ratio of the grinding balls to the raw pearl powder suspension was 1:1. The ball mill was used for grinding at a speed of 1800r / min for 90min at a temperature of 20℃ to obtain a pretreated pearl powder slurry.

[0132] (3) Place the pearl powder slurry in a forced-air drying oven and dry it at 60°C for 24 hours. After sieving, the pretreated pearl powder of the present invention is obtained.

[0133] result

[0134] like Figure 1 As shown, compared to the original pearl powder, the pretreated pearl powder has a significantly reduced particle size, with a size of only about 500 nanometers, and its morphology changes from granular to regular spherical.

[0135] Example 2.

[0136] In this embodiment, to verify that the formation and stability of Pickering emulsion are affected by the particle size and micromorphology of solid particles, a Pickering emulsion stabilized with pretreated pearl powder based on the present invention (sample 1) and a Pickering emulsion stabilized with original pearl powder (sample C1) were prepared.

[0137] The preparation method is as follows:

[0138] (a) Weigh the emulsifier according to the formula in Table 1, add it to deionized water and homogenize it (homogenization rate 10000 r / min, time 2 min) to obtain phase A;

[0139] (b) Weigh out the white oil according to the formula described in Table 1 to obtain phase B;

[0140] (c) Phase A is added to Phase B at room temperature to obtain an oil-water mixture; the resulting oil-water mixture is homogenized at 15000 r / min for 3 min to obtain the final product.

[0141] Table 1 Raw material formulation for Example 2

[0142]

[0143] result

[0144] like Figure 2 As shown in Figure A, the emulsified particles of the original pearl powder-stabilized Pickering emulsion are irregularly elliptical with a particle size exceeding 150 micrometers, indicating low emulsion stability. However, under the same conditions, the Pickering emulsion formed using pearl powder pretreated according to this invention as an emulsifier exhibits excellent stability, with no observed flocculation or aggregation, and the emulsified particle size is significantly reduced and relatively uniform. Further measurement of the particle size of the pretreated pearl powder-stabilized Pickering emulsion according to this invention... Figure 2 B) Emulsified particles with a diameter of 80 to 120 micrometers account for more than 90%.

[0145] according to Figure 2 The following conclusions can be drawn: the formation of Pickering emulsion is related to the particle size of the emulsifier. The Pickering emulsion formed by pearl powder with large particle size (2000-3000 nm) has low stability, while the pearl powder with small particle size (100-800 nm) of the present invention can form a stable Pickering emulsion.

[0146] Example 3.

[0147] In this embodiment, in order to compare the stability of the pretreated pearl powder of the present invention with the common Pickering emulsions (titanium dioxide particles and zinc oxide particles), Pickering emulsions based on the pretreated pearl powder of the present invention (sample 2), Pickering emulsions based on titanium dioxide particles (sample C2), and Pickering emulsions based on zinc oxide particles (sample C3) were prepared.

[0148] The preparation method is as follows:

[0149] (a) Weigh the emulsifier according to the formula in Table 2, add it to deionized water and stir (stir at 500 r / min for 30 min) to obtain phase A;

[0150] (b) Weigh out the white oil according to the formula described in Table 2 to obtain phase B;

[0151] (2) Mix phase A and phase B evenly at room temperature to obtain an oil-water mixture; homogenize the obtained oil-water mixture at 12000 r / min for 3 min to obtain an emulsion.

[0152] Table 2 Raw material formula for Example 3

[0153]

[0154] result

[0155] Figure 3 The images show the appearance (A) and microscopic photograph (B) of the Pickering emulsion obtained by using pretreated pearl powder, titanium dioxide particles, and zinc oxide particles as emulsifiers, respectively, after standing for 24 hours. The Pickering emulsion (sample 2) obtained by pretreated pearl powder of the present invention is basically completely emulsified, with no obvious water separation or oil precipitation. The emulsion particles have small particle size and narrow size distribution, and no flocculation or aggregation was observed. The emulsion has excellent stability.

[0156] When titanium dioxide was used as a solid particulate emulsifier, the system of sample C2 showed obvious stratification in the effluent, and the formed emulsion particles were large in size and had low uniformity, resulting in poor emulsion stability. When zinc oxide particles were used as an emulsifier (sample C3), almost no emulsion formed, and the system showed obvious stratification after standing for 24 hours. Microscopic observation revealed almost no emulsion particles.

[0157] Compared with the solid particles commonly used in cosmetics, the pretreated pearl powder of this invention can be stably suspended in the system, and the Pickering emulsion prepared from it has high stability and high application value in cosmetics.

[0158] Example 4.

[0159] This embodiment aims to verify the stabilizing effect of the pretreated pearl powder of the present invention on different oil-water systems. Therefore, the present invention prepared Pickering emulsions stabilized with the pretreated pearl powder of the present invention, using ethylhexyl palmitate (sample 3), isohexadecane (sample 4), caprylic / capric triglyceride (sample 5), and olive oil (sample 6) as the oil phase, respectively.

[0160] The preparation method is as follows:

[0161] (a) Weigh the pretreated pearl powder, xanthan gum and glycerin according to the formula in Table 3, add them to deionized water and sonicate (ultrasonic power 35%, ultrasonic time 2 min) to obtain phase A, and heat to 70°C.

[0162] (b) Weigh out different oils according to the formulas described in Table 3 to obtain phase B, and heat to 70°C;

[0163] (c) Mix phase A and phase B uniformly at 70°C to obtain an oil-water mixture; keep the obtained oil-water mixture at 10000 r / min for 4 min to obtain an emulsion.

[0164] (d) Stir the emulsion at 300 r / min and cool it to 40°C. Add the preservative of phase C and continue stirring (300 r / min) until it cools to room temperature.

[0165] Table 3 Raw material formulation for Example 4

[0166]

[0167]

[0168] result

[0169] Microscopic images of the pretreated pearl powder of the present invention stabilizing different oil-water systems to form emulsions when used as an emulsifier are shown below. Figure 4 As shown in the figure. The results indicate that samples 3-6 all formed a large number of emulsion particles, and the size of the emulsion particles in each sample was relatively uniform, indicating that a stable Pickering emulsion was formed.

[0170] according to Figure 4 The following conclusions can be drawn: When the pretreated pearl powder of the present invention is used as a Pickering emulsifier, it can stabilize the oil-water system commonly used in cosmetics. The oil phase can be alkane oils, ester oils, natural oils, etc. When the emulsifier content is low (only 0.5% of the total mass of the emulsion), it can form emulsion particles with high uniformity.

[0171] Example 5.

[0172] This embodiment aims to verify the stabilizing effect of the pretreated pearl powder of the present invention on silicone oil / water systems that are difficult to stabilize with ordinary emulsifiers. The silicone oil used in this embodiment is polydimethylsiloxane with a viscosity of 250 (250 cp).

[0173] Therefore, the present invention prepared a Pickering emulsion stabilized by pretreated pearl powder based on the present invention (sample 7), an emulsion stabilized by Tween 80 (sample C4), and an emulsion stabilized by Brij 72 / 721 (sample C5).

[0174] The preparation method is as follows:

[0175] (a) Weigh the A phase component according to the formula in Table 4, add it to deionized water and homogenize it (homogenize at 10000 r / min for 5 min) to obtain the A phase, and heat it to 75°C;

[0176] (b) Weigh the B phase component according to the formula described in Table 4 to obtain the B phase, and heat it to 75°C;

[0177] (c) Mix phase A and phase B uniformly at 75°C to obtain an oil-water mixture; keep the obtained oil-water mixture at 15000 r / min for 2 min to obtain an emulsion.

[0178] Table 4 Raw material formulation for Example 5

[0179]

[0180]

[0181] result

[0182] Microscopic images of a stable silicone oil / water emulsion after one month of storage, using pretreated pearl powder, Tween 80, and Brij 72 / 721 as emulsifiers, according to the present invention. Figure 5 As shown, in the system with Tween 80 and Brij 72 / 721 added, there is essentially no formation of emulsion particles. However, when the pretreated pearl powder of this invention is used as a Pickering emulsifier, the emulsion particles formed are spherical, and the particle size of the emulsion particles is small and highly uniform.

[0183] according to Figure 5 The following conclusion can be drawn: After one month of storage, the pretreated pearl powder of the present invention can still stabilize the dimethyl silicone oil / water system that is difficult to stabilize with common emulsifiers (such as Tween 80, Brij 72 / 721) in cosmetics.

[0184] Example 6.

[0185] This embodiment aims to verify the stabilizing effect of the pretreated pearl powder of the present invention on oil-water systems with a high oil-to-water ratio. Therefore, the present invention prepared Pickering emulsions stabilized with the pretreated pearl powder of the present invention at different oil-to-water ratios.

[0186] The preparation method is as follows:

[0187] (a) Weigh the pretreated pearl powder of the present invention according to the formula described in Table 5, add it to deionized water and perform ultrasonic treatment (ultrasonic power 35%, ultrasonic time 2 min) to obtain phase A;

[0188] (b) Weigh out different amounts of squalane according to the formulations described in Table 5 to obtain phase B;

[0189] (c) Mix phase A and phase B uniformly at room temperature to obtain an oil-water mixture; homogenize the obtained oil-water mixture at 15000 r / min for 6 min to obtain an emulsion.

[0190] Table 5 Raw material formulation for Example 6

[0191]

[0192]

[0193] result

[0194] Microscopic images of the pretreated pearl powder stabilized squalane / water system forming emulsions under different oil-water mass ratios (40%, 60%, 80%, 85%) according to the present invention are shown below. Figure 6 As shown, samples 8-11 all formed relatively uniform emulsion particles, with the only difference being the size of the emulsion particles. The emulsion particles were small in size and uniformly spherical, indicating high stability of the emulsion.

[0195] according to Figure 6 The following conclusion can be drawn: When the pretreated pearl powder of the present invention is used as a Pickering emulsifier, it can stabilize a squalane / water system with an oil phase mass ratio of up to 85%.

[0196] Example 7.

[0197] This embodiment aims to verify the skin irritation of the pretreated pearl powder-stabilized Pickering emulsion of the present invention. The chorioallantoic membrane assay of chicken embryos was used to evaluate the irritation of the emulsion. The present invention used the pretreated pearl powder-stabilized Pickering emulsion (sample 12) and the Brij 72 / 721 emulsifier-stabilized emulsion (sample C6) based on the present invention for testing.

[0198] The preparation method is as follows:

[0199] (a) Weigh the A phase component according to the formula in Table 6, add it to deionized water, heat to 80°C, stir at 500 r / min for 20 min to obtain phase A;

[0200] (b) Weigh out the B phase components according to the formula in Table 6, heat to 80°C, and stir at 500 r / min for 20 min to obtain the B phase;

[0201] (c) Mix phase A and phase B evenly at 80°C to obtain an oil-water mixture; keep the obtained oil-water mixture at 15500 r / min for 3 min to obtain an emulsion, and then stir at 300 r / min to cool to room temperature.

[0202] Table 6 Raw material formula for Example 7

[0203]

[0204]

[0205] Test Method: Chicken embryo chorioallantoic membrane test. The test method refers to the endpoint assessment method of chicken embryo chorioallantoic membrane test for eye irritation / corrosiveness in cosmetics, SN / T 2329—2009. Select appropriate materials and equipment. Apply 0.3 mL of emulsion directly to the chorioallantoic membrane, ensuring at least 50% of the chorioallantoic membrane surface is covered. After 3 minutes, gently rinse the emulsion on the chorioallantoic membrane with physiological saline and observe the degree of change in each toxic effect. Calculate the endpoint score (ES) using the endpoint evaluation method, and retain the results to two decimal places.

[0206] Score per chicken embryo = Degree of hemorrhage, coagulation, and vascularization observed in each chicken embryo;

[0207] ES = the average of the mathematical sums of the scores of the 6 chicken embryos.

[0208] result

[0209] The chorionic allantoic membrane vascular reaction images of samples 12 and C6 are shown below. Figure 7 As shown in Table 7, the results of the endpoint scoring method evaluation are as follows (the chorioallantoic membrane vascular reaction map scores of the six chicken embryos were all the same).

[0210] Table 7. Evaluation Results of the Endpoint Scoring Method

[0211]

[0212] As shown in Table 7, both the pretreated pearl powder-stabilized Pickering emulsion and the Brij 72 / 721 emulsifier-stabilized emulsion of the present invention are classified as non-irritating / mildly irritating. However, the Brij 72 / 721 emulsifier-stabilized emulsion showed slight vascular dissolution after 3 minutes when applied to the chorioallantoic membrane of chicken embryos. Figure 7 B), the endpoint score (ES) of the Brij72 / 721 emulsifier-stabilized emulsion was higher than that of the pearl powder-stabilized Pickering emulsion.

[0213] according to Figure 7 The following conclusions can be drawn from Table 7: Pearl powder, when used as an emulsifier instead of traditional surfactants, can stabilize emulsions and reduce their irritation.

[0214] discuss

[0215] This invention uses pearl powder (with a particle size in the range of 100 nanometers to 800 nanometers) obtained by simple mechanical ball milling pretreatment as a solid particulate emulsifier for Pickering emulsion, and obtains a uniform Pickering emulsion by simple oil-water phase homogenization.

[0216] This invention uses unmodified (e.g., alkylated or hydrophobically modified) pearl powder as a single emulsifier, making the process simple. It can form stable Pickerling emulsions in different oil-water systems and with different oil-water ratios. The stability of the emulsions of this invention is significantly improved compared to emulsions prepared using conventional Pickerling emulsifiers (such as titanium dioxide and zinc oxide) and ordinary emulsifiers (such as Tween 80 and Brij 72 / 721). Furthermore, due to the non-toxic and non-irritating nature of pearl powder itself, the Pickerling emulsions of this invention have low skin irritation.

[0217] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A Pickering emulsion stabilized based on pearl powder, characterized in that, The emulsion comprises: pearl powder, oil, and water as emulsifiers; The pearl powder has a particle size between 200 nanometers and 700 nanometers, and its microstructure is a regular spherical shape. The pearl powder has a mass concentration of 0.2% to 4%, and the oil in the emulsion has a mass concentration of 40% to 90%. The oils in the emulsion are selected from alkane oils, ester oils, natural oils, polydimethylsiloxane, or combinations thereof; The alkane oils mentioned herein are selected from the following group: different types of mineral oil, isohexadecane, isooctane, isododecane, isoeicosane, squalane, or combinations thereof; The ester oils mentioned are selected from the group consisting of: ethylhexyl palmitate, caprylic / capric triglyceride, isopropyl palmitate, isopropyl myristate, triethylhexyl glycerol, pentaerythritol tetraethylhexyl ester, ethyl stearate, butyl stearate, ethyl oleate, ethyl linoleate, isopropyl linoleate, or combinations thereof. The natural oils mentioned are selected from the group consisting of: olive oil, castor oil, peanut oil, palm oil, palm kernel oil, coconut oil, sunflower seed oil, sesame oil, soybean oil, almond oil, avocado oil, evening primrose oil, rice bran oil, macadamia seed oil, wheat germ oil, argan kernel oil, kukui nut oil, rice germ oil, almond oil, olive fruit oil, corn germ oil, rapeseed oil, peach kernel oil, safflower oil, grape seed oil, peony seed oil, flaxseed oil, mango oil, meadowfoam seed oil, jojoba seed oil, cocoa seed oil, rosehip oil, or combinations thereof; Furthermore, the pearl powder mentioned is pretreated pearl powder, and the pretreatment includes the following steps: (a) Provide raw pearl powder, add it to a solvent, and prepare a suspension of raw pearl powder; wherein the solvent is anhydrous ethanol aqueous solution with a concentration of 50% to 100 wt%; (b) The suspension of the original pearl powder from step (a) is mechanically ball-milled and dried to obtain pretreated pearl powder.

2. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The emulsion contains glycerin, xanthan gum, or a combination thereof.

3. The Pickering emulsion based on pearl powder stabilization as described in claim 1, characterized in that, The Pickering emulsion contains over 90% emulsified particles with a particle size of 80 to 120 micrometers.

4. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The pearl powder has a mass concentration of 0.3% to 3.5%. The oil concentration in the Pickering emulsion is 40% to 70%.

5. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The pearl powder has a mass concentration of 0.4% to 3%.

6. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The alkane-based oils mentioned are white oil, isohexadecane, and squalane.

7. The Pickering emulsion based on pearl powder stabilization as described in claim 1, characterized in that, The ester oils mentioned are ethylhexyl palmitate and caprylic / capric triglyceride.

8. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The natural oil mentioned is olive oil.

9. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The Pickering emulsion comprises: Oil content: 40%~90%; Pearl powder 0.2%~4%; Glycerin 0%–5%; Xanthan gum 0%–1%.

10. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The Pickering emulsion comprises: Oil content: 40%~90%; Pearl powder 0.4%~3%; Glycerin 0%–5%; Xanthan gum 0%–1%; The oils are selected from the following group: white oil, polydimethylsiloxane, isohexadecane, squalane, ethylhexyl palmitate, caprylic / capric triglyceride, and olive oil.

11. The pearl powder-stabilized Pickering emulsion as described in claim 1, characterized in that, The squalane is selected from the group consisting of: synthetic squalane, sucrose squalane, and plant-based squalane.

12. A method for preparing a pearl powder-stabilized Pickering emulsion as described in any one of claims 1-11, comprising the following steps: (a) Provide pearl powder, add it to water as phase A, and use oil as phase B; The pearl powder mentioned above is pretreated pearl powder, and the pretreatment includes the following steps: (a) Provide raw pearl powder, add it to a solvent, and prepare a suspension of raw pearl powder; wherein the solvent is anhydrous ethanol aqueous solution with a concentration of 50% to 100 wt%; (b) The suspension of the original pearl powder from step (a) is mechanically ball-milled and dried to obtain pretreated pearl powder; (b) Phase A and Phase B are mixed and homogenized to obtain Pickering emulsion.

13. A cosmetic composition, characterized in that, The cosmetic composition comprises any one of the pearl powder-stabilized Pickering emulsions according to claims 1-11.

14. The cosmetic composition according to claim 13, characterized in that, The cosmetic composition comprising a pearl powder-stabilized Pickering emulsion includes: a skin lotion, a skin cream, a sunscreen, or a combination thereof.

15. Use of the pearl powder-stabilized Pickering emulsion according to any one of claims 1-11 in the preparation of a cosmetic composition.

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