Preparation method of smooth spherical elastomer particles

Abstract

The invention relates to the technical field of organic polymer materials, and particularly discloses a preparation method of smooth spherical elastomer particles. The preparation method comprises the following steps: firstly, respectively preparing a pre-dispersed emulsion I and a pre-dispersed emulsion II, and then preparing the pre-dispersed emulsion I and the pre-dispersed emulsion II into the spherical polydimethylsiloxane cross-linked polymer particle dispersion liquid. And cooling the spherical polydimethylsiloxane cross-linked polymer particle dispersion liquid to 1-5 DEG C, adding a methyl alkoxy oligomer according to the weight part ratio of the spherical polydimethylsiloxane cross-linked polymer particle dispersion liquid to the methyl alkoxy oligomer of 100: (3-10), uniformly dispersing, heating to 55-60 DEG C, carrying out heat preservation reaction for 2-4 hours, separating to obtain wet particles, and drying to obtain the spherical polydimethylsiloxane cross-linked polymer particles. The smooth spherical elastomer particles are obtained. The method provided by the invention can improve the dispersibility and fluidity of the spherical elastomer particles.

Description

Technical Field

[0001] The present invention relates to the technical field of organic polymer materials, and in particular to a method for preparing a smooth spherical elastomer particle. Background Art

[0002] The smooth spherical elastomer particle is a spherical particle formed by special modification on the surface of a three-dimensional cross-linked polydimethylsiloxane polymer. Dispersing and swelling the smooth spherical elastomer particle into cyclic silicone oil, linear silicone oil or other oils can produce cosmetics with unique ductility, film-forming property, oil absorption property, soft skin feel and smooth touch feeling, including lip gloss, lip mud, loose powder, powder cake, skin care lotion, eye shadow, etc.

[0003] Currently, silicone elastomers are mainly non-spherical particles, and their texture is relatively soft and the smooth feeling is poor, so their application scope is greatly limited. Solving the smooth feeling of silicone elastomers is the key to expanding their application scope. Generally, powders such as spherical silica and spherical polymethylsilsesquioxane are added to improve the powder feeling or coating feeling during their application.

[0004] In the related art, CN102883778A discloses a foundation composition containing a water-repellent silicone elastomer powder, which is composed of spherical silicone elastomer particles and polyorganosilsesquioxane coated on the surface of the elastomer particles. The polyorganosilsesquioxane is further condensed by hydrolysis with tetraalkoxysilane and at least one silylating agent. The obtained cosmetic foundation composition has good particle average degree, softness and spreadability, but the spreading effect has a strong smooth feeling and the soft focus effect of the makeup is general.

[0005] CN109399648A discloses a method for preparing micron-sized monodisperse porous silica microspheres. The porous silica microspheres prepared by this method are round and regular in shape, and the particle size distribution is uniform, having a good coating feeling. The above-mentioned microspheres such as spherical silica and spherical polymethylsilsesquioxane are resinous hard materials, which cannot provide a soft texture.

[0006] Although the above methods can prepare micron-sized spherical elastomer particles, due to reasons such as the soft structure of the polydimethylsiloxane cross-linked elastomer itself, after demulsification and drying, the powders are easily adsorbed and agglomerated together and are difficult to be redispersed, which restricts their application. Summary of the Invention

[0007] In order to improve the dispersibility of spherical elastomer particles, the present application provides a method for preparing a smooth spherical elastomer particle.

[0008] A method for preparing a smooth spherical elastomer particle provided by the present application adopts the following technical scheme: A preparation method of a smooth spherical elastomer particle, comprising the following steps: S1. Prepare a pre-dispersed emulsion I. The pre-dispersed emulsion I comprises raw materials in the following weight parts: 10 - 20 parts of an emulsifier, 8 - 10 parts of nano-silica, 18 - 22 parts of polydimethylsiloxane, 70 - 100 parts of polydimethylsiloxane alcohol; 100 parts of deionized water; In proportion, after mixing nano-silica, the emulsifier, and deionized water evenly, add polydimethylsiloxane and polydimethylsiloxane alcohol, and disperse evenly to obtain the pre-dispersed emulsion I; S2. Prepare a pre-dispersed emulsion II. The pre-dispersed emulsion II comprises raw materials in the following weight parts: 18 - 20 parts of an emulsifier, 8 - 10 parts of nano-silica, 2 - 10 parts of methacrylate, 1 - 5 parts of methacryloyloxyethyl trimethyl ammonium chloride, 100 parts of deionized water; In proportion, after mixing nano-silica, the emulsifier, and deionized water evenly, add methacrylate and methacryloyloxyethyl trimethyl ammonium chloride, and disperse evenly to obtain the pre-dispersed emulsion II; S3. Cool the pre-dispersed emulsion I and the pre-dispersed emulsion II to 1 - 5 °C respectively, mix them evenly according to the weight part ratio of pre-dispersed emulsion I:pre-dispersed emulsion II = 100:(5 - 20), heat up to 75 - 82 °C and keep the temperature for reaction to obtain a spherical polydimethylsiloxane cross-linked polymer particle dispersion; S4. Cool the spherical polydimethylsiloxane cross-linked polymer particle dispersion to 1 - 5 °C, add methyl alkoxy oligomer according to the weight part ratio of spherical polydimethylsiloxane cross-linked polymer particle dispersion:methyl alkoxy oligomer = 100:(3 - 10), disperse evenly and then heat up to 55 - 60 °C, keep the temperature for reaction for 2 - 4 h, separate to obtain wet particles, and dry to obtain the smooth spherical elastomer particles.

[0009] By adopting the above technical solutions, emulsifiers are used in both S1 and S2. By reducing the interfacial tension, stable emulsions are formed to prevent the agglomeration of nano-silica and polymers in the initial mixing stage, ensuring the uniform dispersion of particles. Nano-silica can be embedded in the polymer matrix to reduce particle deformation and maintain sphericity. The low-temperature mixing at 1 - 5 °C can inhibit the premature crosslinking of prepolymers, ensuring the physical stability of the emulsions of S1 and S2 during mixing and avoiding phase separation. Heating S3 to 75 - 82 °C can initiate free radical polymerization and silicone crosslinking to form a core-shell structure with PDMS as the core and a shell layer containing cationic monomers. Moreover, in the S3 step, by controlling the mixing ratio of the two-phase emulsion, the particle size and monodispersity of the final particles are adjusted. Heating S4 to 55 - 60 °C helps the hydrolysis and condensation of methylalkoxysiloxane oligomers to form a hydrophobic silicone oxide coating on the particle surface, reducing the surface energy, decreasing the van der Waals force and hydrogen bond interaction between particles, and enhancing the fluidity. Therefore, the smooth spherical elastomer particles prepared by this method have excellent dispersibility, fluidity and ball bearing characteristics. Adding these particles to cosmetics such as ointments, loose powders, and emulsions can reduce internal stress, improve the touch, and provide an excellent velvet smoothness and soft focus effect, forming a natural makeup. Therefore, they are very suitable as cosmetic raw materials.

[0010] In a specific feasible embodiment, the emulsifier adopts a non-ionic emulsifier.

[0011] By adopting the above technical solutions, the methacryloyloxyethyl trimethyl ammonium chloride used in S2 carries a positive charge. If an anionic emulsifier is used, emulsion demulsification or particle aggregation will occur due to electrostatic attraction. The non-ionic emulsifier does not carry a charge, avoiding charge conflicts with cationic monomers or the hydroxyl groups on the surface of nano-silica, and ensuring the stability of the S3 step. In S3, the emulsion needs to be cooled to 1 - 5 °C before mixing, and S3 and S4 need to be heated to 75 - 82 °C and 55 - 60 °C for polymerization reactions. By using a non-ionic emulsifier, the emulsion can remain stable or the integrity of the interfacial film can be maintained at high or low temperatures. Moreover, the non-ionic emulsifier can effectively reduce the oil-water interfacial tension, promote the spheroidization of emulsion droplets, and will not leave residual charges or polar groups on the particle surface, ensuring the uniform coating of methylalkoxysiloxane oligomers and reducing the defects of the modified layer caused by uneven surface polarity, thereby enhancing the smoothness and fluidity of the particles.

[0012] In a specific feasible embodiment, the non-ionic emulsifier is fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether.

[0013] By adopting the above technical solution, the long hydrophilic chains of fatty alcohol polyoxyethylene ether and alkylphenol polyoxyethylene ether can form a thick hydration layer around the nano-silica, and inhibit the aggregation of nano-silica through steric hindrance. Different lengths of alkyl chains in fatty alcohol polyoxyethylene ether, that is, different EO numbers, result in different water-soluble characteristics of the product in the system. The more the EO number, the stronger the water solubility of the product. Usually, when EO is 6 or less, AEO is oil-soluble. In this application, fatty alcohol polyoxyethylene ether AEO7 is preferably used as a water-soluble emulsifier and has certain oil-soluble characteristics, providing conditions for the polymerization of MMA and methyl acryloyloxyethyl trimethyl ammonium chloride to obtain a cationic polymer and polymerizing and modifying the surface of nano-silica.

[0014] In a specific feasible embodiment, the viscosity of the polydimethylsiloxane at 25 °C is 0.65 - 1.5 m 2 / s.

[0015] By adopting the above technical solution, in the pre-dispersed emulsion I, the PDMS with the above viscosity is more easily sheared and dispersed into tiny droplets by the emulsifier to form a homogeneous emulsion, avoiding insufficient emulsifier wrapping or excessive dispersion energy consumption due to too high viscosity. Moreover, the above viscosity can endow PDMS with certain cohesion, reduce droplet coalescence during the high-speed dispersion stage, and maintain the monodispersity of the emulsion droplets, providing a template basis for the subsequent core-shell structure. It is found in this application that by adopting the polydimethylsiloxane within the above viscosity range, the smoothness and fluidity of the particles can be further improved.

[0016] In a specific feasible embodiment, the methyl alkoxysilane oligomer is a methyltrimethoxysilane oligomer, which is prepared according to the following steps: Mix methyltrimethoxysilane and methanol evenly according to a molar ratio of 2:(1 - 1.2), add water and an acid catalyst, heat to 65 - 80 °C, and react for 3.5 - 4 h to obtain the methyltrimethoxysilane oligomer.

[0017] By adopting the above technical solution, 3 mol of water is required for the hydrolysis of MTMS to generate 3 mol of methanol, while the molar ratio of methanol to MTMS in this application is slightly lower than the stoichiometry. By restricting the amount of methanol, the hydrolysis rate is controlled to avoid the risk of gelation caused by excessive condensation. Accelerated hydrolysis and condensation at 65 - 80 °C, but not exceeding the boiling point of MTMS, to avoid the imbalance of the ratio caused by violent volatilization. This temperature range ensures the full progress of the reaction, while inhibiting side reactions, is conducive to the formation of oligomers rather than high-polymerization-degree products, and improves its permeability and film-forming uniformity in S4.

[0018] In a specific feasible embodiment, the acid catalyst is nitric acid or hydrochloric acid.

[0019] By adopting the above technical solutions, both nitric acid and hydrochloric acid are strong acids, which can quickly protonate the methoxy groups in MTMS, significantly reduce the hydrolysis energy barrier, promote the hydrolysis of silane to generate active silanols, and at the same time drive the condensation reaction to form Si-O-Si bonds. Nitric acid can oxidize some intermediate products during the catalysis process, reduce the formation of branched or cyclic structures, and facilitate the uniformity of subsequent particle surface modification. The weak coordination effect of chloride ions in hydrochloric acid can stabilize the condensation intermediates, enabling the condensation reaction to proceed step by step and avoiding local over-crosslinking.

[0020] In a specific feasible embodiment, the degree of polymerization of the methyltrimethoxysilane oligomer is 7-8.

[0021] By adopting the above technical solutions, the methyltrimethoxysilane oligomer within this degree of polymerization range can not only meet the functional requirements of smooth surface modification but also adapt to the process conditions, endowing the particles with certain flexibility and rigidity. When the particles are compressed, they can undergo elastic deformation and recover, maintaining the integrity and smoothness of the particle surface.

[0022] In a specific feasible embodiment, in the S1 step, after adding polydimethylsiloxane and polydimethylsiloxanol, the oil-water ratio is maintained at (0.9-1):1; in the S2 step, after adding methacrylate and methacryloyloxyethyltrimethylammonium chloride, the oil-water ratio is maintained at (0.9-1):1.

[0023] By adopting the above technical solutions, when the oil-water ratio is (0.9-1):1, the system is in a critical state between water-in-oil and oil-in-water. The emulsifier can be quickly adsorbed at the interface to form a bicontinuous phase or uniform emulsion droplets. The uniform emulsion droplets ensure regular particle morphology and few surface defects after polymerization. Combined with the modification of the siloxane oligomer in S4, the coefficient of friction is further reduced, significantly enhancing the smoothness of the particles.

[0024] In summary, the present application has the following beneficial effects: 1. The smooth spherical elastomer particles prepared in the present application have excellent dispersibility, fluidity, and ball bearing characteristics. Adding these particles to cosmetics such as ointments, loose powders, and emulsions can reduce internal stress, improve the touch, and provide an excellent velvet smoothness and soft focus effect, forming a natural makeup. Therefore, they are very suitable as cosmetic raw materials.

[0025] 2. In the present application, it is preferably to use fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether, which can further improve the dispersibility and fluidity of the particles and improve the actual effect of the particles in the application of cosmetic raw materials.

[0026] 3. The viscosity of the polydimethylsiloxane in the present application at 25°C is 0.65-1.5m 2 / s, which can further improve the smoothness and fluidity of the particles. Description of the Drawings

[0027] Figure 1 This is the electron micrograph of the smooth spherical elastomer particles in Example 1 of the present application; Figure 2 This is the picture of the actual effect of applying the smooth spherical elastomer particles in Example 1 of the present application on the experimental skin. Detailed Description of the Invention

[0028] The present application will be further described in detail below in conjunction with examples and comparative examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, those skilled in the art's various equivalent modifications of the present invention all fall within the scope defined by the appended claims of the present application.

[0029] Examples

[0030] Example 1: In this example, a methyl alkoxysilane oligomer was prepared in the following steps: In a container equipped with a condensing reflux device and a thermometer, methyltrimethoxysilane and methanol were respectively added in a molar ratio of 2:1, and stirred and mixed evenly to obtain a mixed solution. Water was added to the mixed solution in a molar ratio of water:methanol = 3:1, and then nitric acid was added in a molar ratio of methanol:nitric acid = 100:3. The reaction was carried out at 80 °C for 3.5 h to obtain a methyltrimethoxysilane oligomer with a polymerization degree n of 8, and the molecular formula is .

[0031] This example provides a method for preparing smooth spherical elastomer particles, including the following steps: S1, preparing the pre-dispersed emulsion I. Weigh the following raw materials: 10 g of AEO7, 10 g of nano-silica, 20 g of polydimethylsiloxane, 80 g of polydimethylsiloxane alcohol, and 100 g of deionized water. According to the above ratio, after mixing AEO7 and deionized water evenly, nano-silica was added, and dispersed evenly at high speed. Then, polydimethylsiloxane and polydimethylsiloxane alcohol were added, and the oil-water ratio was maintained at 1:1, and dispersed evenly at high speed to obtain the pre-dispersed emulsion I. Among them, the viscosity of polydimethylsiloxane at 25 °C is 0.65 m 2 / s.

[0032] S2, preparing the pre-dispersed emulsion II. Weigh the following raw materials: 20 g of AEO7, 8 g of nano-silica, 10 g of methacrylate, 3 g of methacryloyloxyethyltrimethylammonium chloride, and 100 g of deionized water. According to the above ratio, after mixing AEO7 and deionized water evenly, nano-silica was added, and dispersed evenly at high speed. Then, methacrylate and methacryloyloxyethyltrimethylammonium chloride were added, and the oil-water ratio was maintained at 1:1, and dispersed evenly at high speed to obtain the pre-dispersed emulsion II.

[0033] S3. Cool the pre-dispersed emulsion Ⅰ and the pre-dispersed emulsion Ⅱ to 5°C separately in a cycle, mix them according to the weight ratio of pre-dispersed emulsion Ⅰ: pre-dispersed emulsion Ⅱ = 100:15, disperse them evenly at high speed, then heat up to 80°C and keep the temperature for reaction for 2 h to obtain a dispersion of spherical polydimethylsiloxane cross-linked polymer particles.

[0034] S4. Cool the dispersion of spherical polydimethylsiloxane cross-linked polymer particles to 5°C, and add the methyl alkoxy oligomer to the dispersion of spherical polydimethylsiloxane cross-linked polymer particles according to the weight ratio of dispersion of spherical polydimethylsiloxane cross-linked polymer particles: methyl alkoxy oligomer = 100:8. After dispersing evenly, heat up to 560°C, keep the temperature for reaction for 2 h, then perform pressure filtration and separation to obtain wet particulate matter, and dry it with hot air flow to obtain smooth spherical elastomer particles.

[0035] The smooth spherical elastomer particles of this example can be evenly dispersed in water, and have excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 6.0 μm.

[0036] Example 2: The difference between this example and Example 1 is only that in the pre-dispersed emulsion Ⅰ and the pre-dispersed emulsion Ⅱ of this example, AEO7 is replaced with an equal amount of AEO12. During the dispersion and emulsification process of this example, since the AEO12 used is easily soluble in the oil phase and difficult to dissolve in the water phase, the emulsion stability is poor. The obtained smooth spherical elastomer particles can be evenly dispersed in water, and have good spreading performance. Measured by a particle size distribution analyzer Multisizer, the volume average particle size of the particles is 15.0 μm.

[0037] Example 3: The difference between this example and Example 1 is only that in the pre-dispersed emulsion Ⅰ and the pre-dispersed emulsion Ⅱ of this example, AEO7 is replaced with an equal amount of alkylphenol polyoxyethylene ether APEO (purchased from BASF Chemical OP-10). The smooth spherical elastomer particles of this example can be evenly dispersed in water, and have excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 9.5 μm.

[0038] Example 4: The difference between this example and Example 1 is only that in the pre-dispersed emulsion Ⅰ and the pre-dispersed emulsion Ⅱ of this example, AEO7 is replaced with an equal amount of sodium stearoyl glutamate. During the dispersion and emulsification process of this example, since the sodium stearoyl glutamate used is an anionic emulsifier, the emulsion stability is poor. The obtained smooth spherical elastomer particles can be evenly dispersed in water, and have good spreading performance. Measured by a particle size distribution analyzer Multisizer, the volume average particle size of the particles is 22.0 μm.

[0039] Example 5: The difference between this example and Example 1 is only that the viscosity of the polydimethylsiloxane in this example at 25 °C is 1.3 m 2 / s. The smooth spherical elastomeric particles in this example can be evenly dispersed in water, with good spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 3.5 μm.

[0040] Example 6: The difference between this example and Example 1 is only that the viscosity of the polydimethylsiloxane in this example at 25 °C is 1.5 m 2 / s. The smooth spherical elastomeric particles in this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 18.4 μm.

[0041] Example 7: The difference between this example and Example 1 is only that the viscosity of the polydimethylsiloxane in this example at 25 °C is 1.65 m 2 / s. The particle size of the smooth spherical elastomeric particles in this example was measured by a particle size distribution analyzer Multisizer. The particles can be evenly dispersed in water, with good spreading performance, and the measured volume average particle size was 23.2 μm.

[0042] Example 8: The difference between this example and Example 1 is only that in the preparation process of the methyl alkoxy oligomer in this example, an equal amount of hydrochloric acid was used to replace nitric acid. The smooth spherical elastomeric particles in this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 6.5 μm.

[0043] Example 9: The difference between this example and Example 1 is only that the methyl alkoxy oligomer was prepared in advance in the following steps: In a container equipped with a condensing reflux and a thermometer, methyltrimethoxysilane and methanol were respectively added in a molar ratio of 2:1.2, and stirred and mixed evenly to obtain a mixed solution. According to the molar ratio of water:methanol = 3:1, water was added to the mixed solution, and then according to the molar ratio of methanol:nitric acid = 100:3, nitric acid was added, and the reaction was carried out at 65 °C for 4 h to obtain a methyltrimethoxysilane oligomer with a polymerization degree n of 7, and the molecular formula is .

[0044] The smooth spherical elastomeric particles in this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 5.3 μm.

[0045] Example 10: The difference between this example and Example 1 is only that in step S1 of this example, after adding polydimethylsiloxane and polydimethylsiloxanol, the oil-water ratio is maintained at 0.8:1; in step S2, after adding methacrylate and methacryloyloxyethyltrimethylammonium chloride, the oil-water ratio is maintained at 0.8:1. The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 5.8 μm.

[0046] Example 11: The difference between this example and Example 1 is only that in step S1 of this example, after adding polydimethylsiloxane and polydimethylsiloxanol, the oil-water ratio is maintained at 0.9:1; in step S2, after adding methacrylate and methacryloyloxyethyltrimethylammonium chloride, the oil-water ratio is maintained at 0.9:1.

[0047] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 6.2 μm.

[0048] Example 12: The difference between this example and Example 1 is only that in step S1 of this example, after adding polydimethylsiloxane and polydimethylsiloxanol, the oil-water ratio is maintained at 1.1:1; in step S2, after adding methacrylate and methacryloyloxyethyltrimethylammonium chloride, the oil-water ratio is maintained at 1.1:1. The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 7.6 μm.

[0049] Example 13: The difference between this example and Example 1 is only that in step S1 of this example, when preparing the pre-dispersed emulsion I, the following weights of raw materials are weighed: 20 g of AEO7, 8 g of nano-silica, 22 g of polydimethylsiloxane, 70 g of polydimethylsiloxanol, and 100 g of deionized water.

[0050] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size is measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size is 6.2 μm.

[0051] Example 14: The difference between this example and Example 1 is only that in step S1 of this example, when preparing the pre-dispersed emulsion I, the following weights of raw materials are weighed: 15 g of AEO7, 9 g of nano-silica, 18 g of polydimethylsiloxane, 100 g of polydimethylsiloxanol, and 100 g of deionized water.

[0052] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 5.9 μm.

[0053] Example 15: The difference between this example and Example 1 is only that in S2 of this example, when preparing the pre-dispersed emulsion II, the following raw materials were weighed: 18 g of AEO7, 10 g of nano-silica, 2 g of methacrylate, 5 g of methacryloyloxyethyl trimethyl ammonium chloride, and 100 g of deionized water.

[0054] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 5.8 μm.

[0055] Example 16: The difference between this example and Example 1 is only that in S2 of this example, when preparing the pre-dispersed emulsion II, the following raw materials were weighed: 19 g of AEO7, 9 g of nano-silica, 6 g of methacrylate, 3 g of methacryloyloxyethyl trimethyl ammonium chloride, and 100 g of deionized water.

[0056] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 6.2 μm.

[0057] Example 17: The difference between this example and Example 1 is only that in S3 of this example, the pre-dispersed emulsion I and the pre-dispersed emulsion II were respectively cooled down to 1 °C by circulation and mixed according to the weight ratio of pre-dispersed emulsion I: pre-dispersed emulsion II = 100:5.

[0058] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 4.6 μm.

[0059] Example 18: The difference between this example and Example 1 is only that in S3 of this example, the pre-dispersed emulsion I and the pre-dispersed emulsion II were respectively cooled down to 3 °C by circulation and mixed according to the weight ratio of pre-dispersed emulsion I: pre-dispersed emulsion II = 100:20.

[0060] The smooth spherical elastomer particles of this example can be evenly dispersed in water, with excellent spreading performance. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 17.3 μm.

[0061] Comparative Example

[0062] Comparative Example 1: The difference between this comparative example and Example 1 is only that the preparation process of the S2 pre-dispersed emulsion II in this comparative example is as follows. Weigh the following raw materials: 20 g of AEO7, 8 g of nano-silica, 3 g of nitric acid, and 100 g of deionized water. According to the above ratio, after mixing the emulsifier and deionized water evenly, then add nano-silica and disperse evenly at high speed, and then add nitric acid. Keep the oil-water ratio at 1:1 and disperse evenly at high speed to obtain the pre-dispersed emulsion II.

[0063] The smooth spherical elastomer particles of this comparative example have a soft, dry and smooth texture and have good spreading property when dispersed in water. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 48.5 μm. It is easy to adsorb and agglomerate in the powder state.

[0064] Comparative Example 2: The difference between this comparative example and Example 1 is only that in S3 of this example, the pre-dispersed emulsion I and the pre-dispersed emulsion II are respectively cooled cyclically to 3°C and mixed according to the weight ratio of pre-dispersed emulsion I: pre-dispersed emulsion II = 100:3. The smooth spherical elastomer particles of this comparative example have a soft, dry and smooth texture and have good spreading property when dispersed in water. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 1.6 μm.

[0065] Comparative Example 3: The difference between this comparative example and Example 1 is only that in S3 of this example, the pre-dispersed emulsion I and the pre-dispersed emulsion II are respectively cooled cyclically to 3°C and mixed according to the weight ratio of pre-dispersed emulsion I: pre-dispersed emulsion II = 100:25. The smooth spherical elastomer particles of this comparative example have a soft, dry and smooth texture and have good spreading property when dispersed in water. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 27.2 μm. It is easy to adsorb and agglomerate in the powder state.

[0066] Comparative Example 4: The difference between this comparative example and Example 1 is only that in S1 of this example, weigh the following raw materials: 10 g of AEO7, 10 g of nano-silica, 3 g of nitric acid, and 100 g of deionized water. According to the above ratio, after mixing the emulsifier and deionized water evenly, then add nano-silica and disperse evenly at high speed, and then add nitric acid. Keep the oil-water ratio at 1:1 and disperse evenly at high speed to obtain the pre-dispersed emulsion I.

[0067] The smooth spherical elastomer particles of this comparative example have a soft, dry and smooth texture, but have poor spreading property when dispersed in water. The particle size was measured by a particle size distribution analyzer Multisizer, and the measured volume average particle size was 45.2 μm. It is easy to adsorb and agglomerate in the powder state.

[0068] Performance detection test For Examples 1-18 and Comparative Examples 1-4, the following performance detections were carried out: 1. The volume average particle size of the smooth spherical elastomer particles was measured by a particle size distribution analyzer Multisizer, and the detection results are shown in Table 1. The smooth spherical elastomer particles of Example 1 were detected by a scanning electron microscope of the Hitachi FlexSEM 1000 II model, as Figure 1 shown.

[0069] 2. The smooth spherical elastomer particles were evenly dispersed in water and allowed to stand, and the spreading property was observed. From excellent to poor, they were: excellent > good > fair > poor. The detection results are shown in Table 1.

[0070] 3. The smooth spherical elastomer particles were freely stacked into a cone through a funnel, and the angle between the conical surface and the horizontal plane was measured. The smaller the angle of repose, the better the fluidity. The detection results are shown in Table 1.

[0071] 4. In this application, a VITRO-SKIN® in vitro skin model was used as the experimental skin. 0.02 g of smooth spherical elastomer particles were evenly applied on the 3 cm × 3 cm experimental skin. After standing for 1 h, 5 persons aged 18-30 were randomly selected. The actual effects on the wrinkles and roughness covering the skin surface were observed with the naked eye, and the actual effects were scored within the range of 0-10 points. The larger the score, the better the concealer and soft focus effects, and the better the natural makeup feeling. The smaller the score, the worse the concealer and soft focus effects. The average value of the scores of 5 persons was recorded. The detection results are shown in Table 1. The actual effect of the smooth spherical elastomer particles of Example 1 applied on the experimental skin is shown as Figure 2 shown.

[0072] Table 1

[0073] Combining Example 1 and Comparative Examples 1-4 and combining with Table 1, it can be seen that compared with Example 1, the volume average particle size and the angle of repose of the particles in Comparative Examples 1, 3 and 4 are significantly larger, and the volume average particle size and the angle of repose of the particles in Comparative Example 2 become smaller. Moreover, the actual effects of Comparative Examples 1-4 on covering the wrinkles and roughness on the skin surface become worse. This shows that using the raw material ratio and steps of Example 1 helps to improve the dispersibility and fluidity of the smooth spherical elastomer particles, and the actual effect is good in the application of cosmetic raw materials.

[0074] As can be seen from Examples 1-18 in combination with Table 1, the volume average particle size of the particles in Examples 1-18 is less than 30 μm, the angle of repose is less than 40°, and the spreadability is good or excellent. This indicates that by using the raw material ratios and process conditions within the range of Examples 1-18, smooth spherical elastomer particles with excellent dispersibility and fluidity can be prepared.

[0075] Compared with Example 1, the scores of Examples 7, 10, and 12 are smaller in terms of covering wrinkles and roughness on the skin surface. This shows that the polydimethylsiloxane used has a viscosity of 0.65 - 1.5 m 2 / s at 25°C, and maintaining the oil-water ratio at (0.9 - 1):1 in Steps S1 and S2 can further improve the actual effect of the smooth spherical elastomer particles in the application of cosmetic raw materials.

[0076] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A method for preparing smooth spherical elastomer particles, characterized in that: The steps include: S1, preparing a pre-dispersed emulsion I, the pre-dispersed emulsion I comprises the following raw materials in parts by weight: 10-20 parts of an emulsifier, 8-10 parts of nano-silicon dioxide, 18-22 parts of polydimethylsiloxane, 70-100 parts of polydimethylsiloxane alcohol; 100 parts of deionized water; according to a certain proportion, after uniformly mixing the nano-silicon dioxide, the emulsifier, and the deionized water, adding the polydimethylsiloxane and the polydimethylsiloxane alcohol, and uniformly dispersing them, to obtain the pre-dispersed emulsion I; S2, preparing a pre-dispersed emulsion II, the pre-dispersed emulsion II comprising the following raw materials in parts by weight: 18-20 parts of an emulsifier, 8-10 parts of nano-silicon dioxide, 2-10 parts of methacrylate, 1-5 parts of methacryloyloxyethyl trimethyl ammonium chloride, and 100 parts of deionized water; after uniformly mixing the nano-silicon dioxide, the emulsifier, and the deionized water according to proportion, adding methacrylate and methacryloyloxyethyl trimethyl ammonium chloride, and uniformly dispersing to obtain a pre-dispersed emulsion II; S3, respectively cooling the pre-dispersed emulsion I and the pre-dispersed emulsion II to 1-5° C., mixing them uniformly in a weight ratio of pre-dispersed emulsion I: pre-dispersed emulsion II = 100: (5-20), heating them to 75-82° C. and then keeping them warm for reaction to obtain a spherical polydimethylsiloxane crosslinked polymer particle dispersion; S4, cooling the spherical polydimethylsiloxane cross-linked polymer particle dispersion to 1-5°C, adding methyl alkoxy oligomer in a weight ratio of spherical polydimethylsiloxane cross-linked polymer particle dispersion: methyl alkoxy oligomer = 100: (3-10), and after uniform dispersion, heating to 55-60°C, keeping the temperature for reaction for 2-4h, separating to obtain wet granules, drying to obtain smooth spherical elastomer particles.

2. The method for preparing the smooth spherical elastic particles according to claim 1, characterized in that: The emulsifier is a non-ionic emulsifier.

3. The method for preparing the smooth spherical elastic particles according to claim 2, characterized in that: The nonionic emulsifier is fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether.

4. The method for preparing the smooth spherical elastic particles according to claim 1, characterized in that: The viscosity of the polydimethylsiloxane at 25°C is 0.65-1.5 m 2 / s.

5. The method for preparing the smooth spherical elastic particles according to claim 1, characterized in that: The methyl alkoxy oligomer is a methyl trimethoxy silane oligomer, which is prepared according to the following steps: methyl trimethoxy silane and methanol are uniformly mixed in a molar ratio of 2: (1-1.2), water and an acid catalyst are added, heated to 65-80° C., and reacted for 3.5-4 hours to obtain a methyl trimethoxy silane oligomer.

6. The method for preparing the smooth spherical elastic particles according to claim 5, characterized in that: The acid catalyst is nitric acid or hydrochloric acid.

7. The method for preparing the smooth spherical elastic particles according to claim 5, characterized in that: The polymerization degree of the methyltrimethoxysilane oligomer is 7-8.

8. The method for preparing the smooth spherical elastic particles according to claim 1, characterized in that: In the step S1, after adding polydimethylsiloxane and polydimethylsiloxane alcohol, the oil-water ratio is maintained at (0.9-1):1; in the step S2, after adding methacrylate and methacryloyloxyethyltrimethylammonium chloride, the oil-water ratio is maintained at (0.9-1):1.

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