Cosmetic loose powder and preparation method therefor

Abstract

Provided are a cosmetic loose powder and a preparation method therefor. The provided cosmetic loose powder comprises at least a filler, an emollient, and a solvent, and does not comprise silylated silica. The bulk density of the cosmetic loose powder is 0.250-0.464 g / cm 3, and the mass percentage content of the solvent in the cosmetic loose powder is 2-20%. In the process of preparing the cosmetic loose powder, a vacuum freeze-drying process is used to dry the solvent. The traditional concept that a loose powder is substantially free of water is discarded, and the approach of using an organosilicon compound to achieve a water-in-powder system is not followed. Instead, a cosmetic loose powder that has a certain solvent content and bulk density, is sufficiently fluffy, and, when applied, offers relatively good adherence.

Description

A loose powder for cosmetics and its preparation method

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411846596.7, filed on December 13, 2024, entitled “A loose powder for cosmetics and a method for preparing the same,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of cosmetic technology, and in particular to a loose powder for cosmetics and a method for preparing the same. Background Technology

[0004] Powder cosmetics can be in the form of dense, block-shaped powder or loose powder. Loose powder cosmetics, also known as setting powder or setting powder, are applied after foundation lotion or cream for touch-ups and finishing touches.

[0005] In existing technologies, the preparation of cosmetic powder products requires the use of solvents (such as water) to complete processes such as raw material mixing, shaping, or transfer, and the solvent is removed in the later stages of the preparation process. Traditionally, it is believed that residual solvent in loose powder will prevent it from being fluffy and affect its usability. Therefore, traditional loose powder is almost solvent-free, and all previously introduced solvents must be removed as much as possible through a drying step at the end of the preparation process. However, it is also because of the loose and fluffy nature of loose powder that its adherence to the skin after application often does not reach its ideal state.

[0006] In recent years, a type of water-in-powder has emerged, using silylated silica (an organosilicon compound, different from the inorganic silica commonly used in cosmetics) as a carrier to achieve a water-in-powder system. The water and polyol content is typically between 30% and 60%. However, this water-in-powder system is prone to drying out, has poor formulation stability, and is prone to agglomeration during transportation and use, forming clumps that affect usability and appearance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this application is to provide a loose powder for cosmetics and its preparation method. This method abandons the traditional concept that loose powder is basically water-free, and does not follow the practice of using organosilicon compounds to achieve a powder-in-water system. Instead, it is based on a vacuum freeze-drying process to prepare a loose powder for cosmetics with a certain solvent content and bulk density, sufficient fluffiness, and good adherence after makeup application.

[0008] The above-mentioned inventive objective of this application is achieved through the following technical solutions:

[0009] In a first aspect, this application provides a loose powder for cosmetics and a method for preparing the same, comprising at least a filler, a moisturizer, and a solvent, wherein the loose powder for cosmetics does not contain silylated silica; the solvent comprises 2-20% by mass in the loose powder for cosmetics, and the bulk density of the loose powder for cosmetics is 0.250-0.464 g / cm³. 3 In the preparation process of the loose powder for cosmetics, a vacuum freeze-drying process is used to dry the solvent in the loose powder for cosmetics.

[0010] Optionally, in the loose powder for cosmetics provided in this application, the solvent content in the loose powder is 5% to 16% by mass, and the bulk density of the loose powder is 0.263 to 0.456 g / cm³. 3 .

[0011] Optionally, in the loose powder for cosmetics provided in this application, the solvent content in the loose powder is 8-14% by mass, and the bulk density of the loose powder is 0.270-0.420 g / cm³. 3 .

[0012] According to a first aspect of this application, the solvent is selected from one or more of deionized water, plant extracts, and plant fermentation broths.

[0013] According to a first aspect of this application, the loose powder for cosmetics further comprises one or more of a surface modifier, a preservative, an antioxidant, a sunscreen, and an active ingredient.

[0014] According to a first aspect of this application, the filler is selected from one or more of mica, synthetic fluorophlogopite, boron nitride, bismuth oxychloride, silica, potassium sodium aluminum silicate, lauroyl lysine, calcium aluminum borosilicate, calcium sodium borosilicate, starch and its derivatives, and plastic microbeads.

[0015] According to a first aspect of this application, the emollient is selected from at least one of plant oils, silicone oils, glyceryl tri(ethylhexanoate), bis-diglyceryl polyacryladiate-2, isononyl isononyl ester, lauryl laurate, hydrogenated polydecene, cetyl ethylhexanoate, diisostearyl malate, glycolipids, and octyldodecyl stearyl oxystearate.

[0016] According to a first aspect of this application, the surface modifier is selected from at least one of triethoxyoctylsilane, polydimethylsiloxane, hydrogenated polydimethylsiloxane, and triisostearic acid isopropoxytitanium salt.

[0017] According to a first aspect of this application, the preservative is selected from at least one of phenoxyethanol, parabens, chlorphenesin, potassium sorbate, sodium benzoate, or preservative synergists; the preservative synergist is selected from at least one of caprylyl glycol, p-hydroxyacetophenone, ethylhexylglycerin, 1,2-hexanediol, capryloyl hydroxamic acid, 1,2-pentanediol, glyceryl caprylate, and cymene.

[0018] According to a first aspect of this application, the antioxidant is selected from at least one of dipalmitoyl hydroxyproline, tocopherol acetate, pentaerythritol tetra(bis-tert-butylhydroxyhydrocinnamic acid) ester, and tocopherol.

[0019] According to a first aspect of this application, the mass fractions of the filler, emollient, surface modifier, preservative, antioxidant, and active ingredient are as follows, by weight: 55-95 parts for filler; 1-20 parts for emollient; 0.01-5 parts for surface modifier; 0.1-2 parts for preservative; 0.05-1 part for antioxidant; 0-5 parts for sunscreen; and 0-5 parts for active ingredient.

[0020] The second aspect of this application provides a method for preparing the loose powder for cosmetics described in the first aspect, comprising the following steps: mixing: providing raw materials for preparing loose powder for cosmetics, mixing to obtain a mixture; filling: filling the mixture into a container according to a preset amount; pre-freezing: pre-freezing the mixture in the container; drying: performing vacuum freeze-drying on the pre-frozen mixture until the mass percentage content of the solvent in the loose powder for cosmetics is reduced to the range described above, thereby obtaining the loose powder for cosmetics.

[0021] According to a second aspect of this application, the step of filling the mixture into the container in a preset amount includes: filling the mixture into the container under the action of gravity or air pressure at room temperature or under heating conditions.

[0022] According to a second aspect of this application, the step of pre-freezing the mixture in the container is performed using liquid nitrogen tunnel freezing, wherein the temperature of the liquid nitrogen freezing is -85 to -70°C.

[0023] According to a second aspect of this application, the step of pre-freezing the mixture in the container is carried out by high-pressure freezing, wherein the temperature of the high-pressure freezing is -20 to -40°C and the pressure is 50 to 100 MPa.

[0024] According to a second aspect of this application, the vacuum negative pressure freeze drying includes at least: using a freeze dryer to freeze-dry a mixture frozen into a solid state, and removing the solvent in the mixture directly into a gaseous state under vacuum to a preset content range.

[0025] In summary, this application includes at least one of the following beneficial technical effects:

[0026] Compared with the prior art, in order to solve the shortcomings of traditional loose powder in terms of poor adherence after makeup application, this application abandons the traditional concept that loose powder is basically free of solvents and provides a cosmetic loose powder with a solvent content of 2-20%, preferably 5-16%, and more preferably 8-14%. At the same time, the inventors have noticed that if the loose powder is dried to the above solvent content using conventional drying methods (such as heat drying), the resulting loose powder does not have fluffiness, and its usability is greatly affected.

[0027] To address this, this application employs a vacuum freeze-drying process to dry the loose powder to the aforementioned solvent content, resulting in a cosmetic loose powder with a content of 0.250–0.464 g / cm³. 3 The preferred value is 0.263–0.456 g / cm³. 3 More preferably, it is 0.270–0.420 g / cm³. 3 The bulk density characteristics of this product not only result in good adherence but also good fluffiness. Vacuum freeze-drying removes solvent-containing materials by directly sublimating the solvent, which has frozen into ice crystals, into a gaseous state without passing through a liquid state. Compared to other drying methods, vacuum freeze-drying optimizes the morphology and energy transfer processes during ice crystal formation and removal, significantly impacting the texture of the loose powder. The loose powder for cosmetics provided in this application maintains sufficient fluffiness while exhibiting good adherence after makeup application. Detailed Implementation

[0028] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0030] In existing technologies, the fluffiness and adherence of loose powder are considered mutually exclusive: residual solvents in loose powder prevent it from being fluffy, affecting its usability. Therefore, traditional loose powders are almost solvent-free, and the final step in the preparation process is to remove as much solvent as possible through a drying step, giving the powder its fluffy and loose characteristics. However, it is precisely because of these fluffy and loose characteristics that the adherence to the skin after application often falls short of expectations.

[0031] According to a first aspect of this application, embodiments of this application provide a loose powder for cosmetics, comprising at least a filler, a moisturizer, and a solvent, wherein the loose powder for cosmetics does not contain silylated silica; the solvent comprises 2-20% by mass in the loose powder for cosmetics, and the bulk density of the loose powder for cosmetics is 0.250-0.464 g / cm³. 3 In the preparation process of the loose powder for cosmetics, a vacuum freeze-drying process is used to dry the solvent in the loose powder for cosmetics.

[0032] In this application, the traditional concept of loose powder being essentially solvent-free is abandoned, and a solvent-containing loose powder with a solvent content of 2-20% is provided. Furthermore, this application employs a vacuum freeze-drying process to dry the solvent in the cosmetic loose powder to the stated solvent content. Vacuum freeze-drying removes the solvent-containing material by directly sublimating the solvent, which has frozen into ice crystals, into a gaseous state without passing through a liquid state, while the material is in a frozen state. Compared to other drying methods, vacuum freeze-drying optimizes the morphology and energy transfer process during ice crystal formation and removal, significantly impacting the texture of the loose powder. This allows the prepared cosmetic loose powder to achieve a texture of 0.250-0.464 g / cm³ while retaining a certain amount of residual solvent. 3 The bulk density. The embodiment of this application provides a product prepared using a vacuum freeze-drying process, with a solvent content of 2-20% and a bulk density of 0.250-0.464 g / cm³.3 This loose powder not only has good volume but also adheres well to the skin after makeup application.

[0033] In some embodiments of this application, the solvent content in the loose cosmetic powder is 5-16% by mass, and the bulk density of the loose cosmetic powder is 0.263-0.456 g / cm³. 3 .

[0034] In some embodiments of this application, the solvent content in the loose cosmetic powder is 8-14% by mass, and the bulk density of the loose cosmetic powder is 0.270-0.420 g / cm³. 3 .

[0035] By further controlling the solvent water content within an optimal range, the bulk density of the loose powder for cosmetics was further optimized, resulting in better overall performance in terms of fluffiness and adherence after makeup application.

[0036] In some embodiments of this application, the solvent is selected from one or more of deionized water, plant extracts, and plant fermentation broth.

[0037] In some embodiments of this application, the loose powder for cosmetics further comprises one or more of the following: surface modifier, preservative, antioxidant, sunscreen, and active ingredient.

[0038] In some embodiments of this application, the filler is selected from one or more of mica, synthetic fluorophlogopite, boron nitride, bismuth oxychloride, silica, potassium sodium aluminum silicate, lauroyl lysine, calcium aluminum borosilicate, calcium sodium borosilicate, starch and its derivatives, and plastic microbeads.

[0039] In some embodiments of this application, the emollient is selected from at least one of plant oils, silicone oils, glyceryl tri(ethylhexanoate), bis-diglyceryl polyacryladiate-2, isononyl isononyl ester, lauryl laurate, hydrogenated polydecene, cetyl ethylhexanoate, diisostearyl malate, glycolipids, and octyldodecyl stearyl oxystearate.

[0040] In some embodiments of this application, the surface modifier is selected from at least one of triethoxyoctylsilane, polydimethylsiloxane, hydrogenated polydimethylsiloxane, and triisostearic acid isopropoxytitanium salt.

[0041] In some embodiments of this application, the preservative is selected from at least one of phenoxyethanol, parabens, chlorphenesin, potassium sorbate, sodium benzoate, or preservative synergists; the preservative synergist is selected from at least one of caprylyl glycol, p-hydroxyacetophenone, ethylhexylglycerin, 1,2-hexanediol, capryloyl hydroxamic acid, 1,2-pentanediol, glyceryl caprylate, and cymene.

[0042] In some embodiments of this application, the antioxidant is selected from at least one of dipalmitoyl hydroxyproline, tocopherol acetate, pentaerythritol tetra(bis-tert-butylhydroxyhydrocinnamic acid) ester, and tocopherol.

[0043] In some embodiments of this application, the active ingredient is selected from heat-sensitive active ingredients or heat-insensitive active ingredients; the heat-sensitive active ingredient is selected from at least one of polypeptide active ingredients, astaxanthin, vitamin A alcohol or its derivatives, vitamin C or its derivatives, and arbutin.

[0044] In some embodiments of this application, the mass parts of the filler, emollient, surface modifier, preservative, antioxidant, and active ingredient range as follows, by weight: 55-95 parts for filler; 1-20 parts for emollient; 0.01-5 parts for surface modifier; 0.1-2 parts for preservative; 0.05-1 part for antioxidant; 0-5 parts for sunscreen; and 0-5 parts for active ingredient.

[0045] According to a second aspect of this application, embodiments of this application also provide a method for preparing the loose powder for cosmetics described in the first aspect, comprising the following steps: mixing: providing raw materials for preparing loose powder for cosmetics, mixing them to obtain a mixture; filling: filling the mixture into a container according to a preset amount; pre-freezing: pre-freezing the mixture in the container; drying: performing vacuum freeze-drying on the pre-frozen mixture until the mass percentage content of the solvent in the loose powder for cosmetics is reduced to the range described above, thereby obtaining the loose powder for cosmetics.

[0046] The raw materials for preparing loose powder for cosmetics can be commercially available or prepared in-house. It is understood that the raw materials for preparing loose powder for cosmetics typically include powder phase components, oil phase components, and aqueous phase components. The raw materials can be mixed using various methods commonly used in existing technologies, such as mechanical stirring, by adding the raw materials step by step and mixing them evenly. Homogenization and defoaming operations can be added during the mixing process. Different mixing methods and steps can be used depending on the raw materials, and this application is not limited to these.

[0047] In the filling step, the preset amount can be set according to the volume of the block powder cosmetic, the container capacity, or the filling requirements. The preset amount for each filling can be the same or different. The step of filling the mixture into the container according to the preset amount includes: filling the mixture into the container under the action of gravity or air pressure at room temperature or under heating conditions.

[0048] In some embodiments of this application, the mixture is heated and then filled into a container by gravity filling. For example, the heating temperature of the mixture can be 50–80°C.

[0049] In some embodiments of this application, the mixture is filled into a container via a pneumatic feeding device. For example, the mixture can be pressed into or sucked into the container by the action of air pressure.

[0050] This application does not limit the specific method by which the material is filled into the container in a preset amount. The material can be forced into the container by air pressure. For example, a pneumatic feeding device includes an inlet pipe, an air pump, and an outlet pipe. The air pump provides the delivery air pressure to draw the material into the pneumatic feeding device through the inlet pipe and then force it into the container through the outlet pipe. Alternatively, the material can be drawn into the container by air pressure. For example, a pneumatic feeding device is connected to the container, and the pneumatic feeding device provides the delivery air pressure to draw the material into the container. Regardless of whether the material is forced into or drawn into the container, the requirements for the material's flowability are low, and excessive solvents are not required, greatly shortening the subsequent drying time and allowing the use of high-temperature sensitive active materials.

[0051] In some embodiments of this application, the pressure in the pneumatic feeding device can be 0.01 to 0.08 MPa. For example, the pressure in the pneumatic feeding device can be 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, 0.05 MPa, 0.06 MPa, 0.07 MPa, 0.08 MPa, or a range consisting of any two of the above values.

[0052] In some embodiments of this application, the viscosity of the material can be 5000 cP to 12000 cP. For example, the viscosity of the material can be 5000 cP, 6000 cP, 7000 cP, 8000 cP, 9000 cP, 10000 cP, 11000 cP, 12000 cP, or a range consisting of any two of the above values.

[0053] Following the filling step, the mixture is pre-frozen, causing the solvent in the mixture to freeze into ice (or ice crystals). In some embodiments of this application, the pre-freezing step of the mixture in the container is performed using liquid nitrogen tunnel freezing, with the temperature of the liquid nitrogen tunnel freezing being -85°C to -70°C.

[0054] A liquid nitrogen tunnel, also known as a liquid nitrogen tunnel-type quick-freezing machine, is a device that uses liquid nitrogen as a cold source and employs a continuous production method. Materials are fed into the quick-freezing tunnel via a conveyor belt, enabling continuous material entry and exit and rapid freezing. This application uses a liquid nitrogen tunnel to perform extremely low-temperature solidification of the filled mixture. The raw material components in the mixture undergo molecular quick-freezing in an extremely low-temperature environment within the liquid nitrogen quick-freezing device. Cosmetic materials contain components such as oils and emulsions. During their freezing and setting process, they experience a maximum ice crystal formation zone, where approximately 80% of the liquid (water, emulsion, etc.) turns into ice. Unlike ordinary freezing, in this application, the molecular quick-freezing process completed within the liquid nitrogen tunnel allows the mixture to rapidly pass through the maximum ice crystal formation zone. The generated ice crystals are evenly distributed, fine, and dense in the powder masterbatch. During the subsequent vacuum freeze-drying process, the fine and uniform characteristics of the ice crystals play a crucial role in maintaining the fluffiness and conformability of the loose powder, resulting in freeze-dried loose powder with good fluffiness and conformability.

[0055] In some embodiments of this application, the step of pre-freezing the mixture in the container is carried out by high-pressure freezing, wherein the temperature of the high-pressure freezing is -20 to -40°C and the pressure is 50 to 100 MPa.

[0056] High-pressure freezing can be performed in commercially available high-pressure freezers, which rapidly freeze materials under predetermined high pressure. The density of ice crystals formed during the freezing process varies depending on the pressure. For example, ice formed from water under normal atmospheric pressure is type I ice crystal, which has a lower density than water itself. However, ice crystals formed from liquid water under higher pressure have a higher density than liquid water; these are type II to VI ice crystals, and their structure is more complex than that of type I ice crystals. Some embodiments of this application employ high-pressure freezing technology. During pre-freezing, pressure is applied to the mixture, causing the solvent (e.g., water) in the mixture to undergo a phase change during freezing, forming more numerous and smaller type II to VI ice crystals. Subsequent vacuum freeze-drying removes these type II to VI ice crystals, resulting in powder with optimal fluffiness and conformability, while also improving its softness.

[0057] Finally, the pre-frozen mixture is subjected to vacuum freeze-drying, which includes at least: using a freeze dryer to freeze-dry the mixture frozen into a solid state, and removing the solvent in the mixture by direct sublimation into a gaseous state under vacuum, until the mass percentage content of the solvent in the cosmetic powder is reduced to the range defined in this application.

[0058] For example, vacuum freeze drying can include freezing, sublimation drying, and desorption drying. Freezing can specifically include freezing at -42℃ to -45℃ for 1 hour to 1.5 hours; sublimation drying can specifically include heating the material to -3℃ to 3℃, the heating process including several first heating stages and several first holding stages, with the first heating stages and first holding stages alternating; the first heating stages are heated at 0.6 to 0.8℃ / min for 15 to 18 minutes, and the first holding time is 1.6 to 1.8 hours; desorption drying can specifically include drying the material at 25℃ to 50℃, the drying process including several second heating stages and several second holding stages, with the second heating stages and second holding stages alternating; the second heating stages are heated at 0.6 to 0.8℃ / min for 15 to 18 minutes, and the second holding time is 1.6 to 1.8 hours.

[0059] Example:

[0060] The following embodiments describe the disclosure of this application in more detail. These embodiments are for illustrative purposes only, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0061] Formulas 1-2:

[0062] For example, this application provides two methods for preparing raw materials, proportions, and mixing methods for cosmetic loose powder.

[0063] The raw material components of loose powder formula 1 for cosmetics are shown in Table 1:

[0064] Table 1. Composition of Formula 1

[0065] Mixing: (1) Heat phase A to 75±5℃; (2) Add phase B to phase A and homogenize and emulsify to 75±5℃; (3) Add phase C to phase (2) and mix evenly to 75±5℃; (4) Cool the material to 50±5℃; (5) Add phase D (which needs to be pre-dissolved) and phase E to phase (4) and mix evenly, and degas under vacuum to 50±5℃; to obtain the material.

[0066] The raw material components of loose powder formula 2 for cosmetics are shown in Table 2:

[0067] Table 2 Formulation 2 Composition

[0068] Mixing: (1) Mix phases B, C and D evenly; (2) Add (1) to A and mix evenly at room temperature; (3) Add phase E to (2) and mix evenly at room temperature; (4) Vacuum degassing at room temperature; obtain the material.

[0069] Examples 1-14:

[0070] Prepare loose powder for cosmetics as follows:

[0071] Mixing: Provide the raw materials according to the raw material components of formula 1 for loose powder for block cosmetics, and mix the raw materials according to the mixing steps to obtain a mixture;

[0072] Filling: Filling the container with the mixture according to the preset amount;

[0073] Pre-freezing: Pre-freezing the mixture in the container;

[0074] Drying: The pre-frozen mixture is subjected to vacuum freeze-drying until the mass percentage content of the solvent in the cosmetic powder is reduced to the range specified, thereby obtaining the cosmetic powder.

[0075] The vacuum freeze-drying process is carried out in a freeze dryer and includes freezing, sublimation drying, and desorption drying. Specifically, freezing involves freezing at -42℃ to -45℃ for 1-1.5 hours. Sublimation drying involves heating the material to -3℃ to 3℃, with the heating process including several first heating stages and several first holding stages, alternating between the first heating stages and the first holding stages. The first heating stage involves heating at 0.6-0.8℃ / min for 15-18 minutes, and the first holding time is 1.6-1.8 hours. Desorption drying involves drying the material at 25℃ to 50℃, with the drying process including several second heating stages and several second holding stages, alternating between the second heating stages and the second holding stages. The second heating stage involves heating at 0.6-0.8℃ / min for 15-18 minutes, and the second holding time is 1.6-1.8 hours.

[0076] The parameters of the filling, pre-freezing and other steps used in Examples 1 to 14, the solvent content in the prepared powder and the bulk density of the powder are recorded in Table 3.

[0077] Comparative Examples 1-3:

[0078] The difference between Comparative Example 1 and Example 1 is that, in the step of drying the solvent in the cosmetic loose powder using a vacuum freeze-drying process, the mass percentage content of the solvent in the cosmetic loose powder is dried to 1%.

[0079] The difference between Comparative Example 2 and Example 1 is that, in the step of drying the solvent in the cosmetic loose powder using a vacuum freeze-drying process, the mass percentage content of the solvent in the cosmetic loose powder is dried to 25%.

[0080] The difference between Comparative Example 3 and Example 1 is that the solvent in the loose powder was dried by heating and drying, and the mass percentage content of the solvent in the loose powder was dried to 14%.

[0081] The solvent content and bulk density of the loose powder prepared by Comparative Examples 1-3 using parameters for filling, pre-freezing, etc. are recorded in Table 3.

[0082] Table 3 Parameter Tables for Examples 1-14 and Comparative Examples 1-3

[0083] Product testing:

[0084] (1) Bulk density test

[0085] Powder bulk density refers to the weight of powder per unit volume and is an important indicator for evaluating the degree of filling between powder particles. The bulk density of the loose powders prepared in Examples 1-14 and Comparative Examples 1-3 was tested using a general-purpose bulk density tester.

[0086] (2) Skin feel assessment

[0087] Volunteers scored and evaluated the fluffiness, makeup adherence, and cotton-like softness of the loose powders prepared in Examples 1-14 and Comparative Examples 1-3.

[0088] Eighty participants, aged 18-45, were randomly selected. Loose powders prepared using Examples 1-14 or Comparative Examples 1-3 were used. The participants rated the looseness, adherence, and softness of the powders. The rating criteria were as follows: 10 points was the maximum score; 1-2 points: very poor; 3-4 points: poor; 5-6 points: average; 7-8 points: good; 9-10 points: very good. The average score of the 80 participants (rounded to one decimal place) was taken as the score for the corresponding item in each example or comparative example. The results are shown in Table 4.

[0089] Table 4. Test results of Examples 1-14 and Comparative Examples 1-3

[0090] As shown in Table 4, the test results in Examples 1-14, using the preparation method of the loose powder provided in this application, involved drying the solvent in the loose powder using a vacuum freeze-drying process until the mass percentage content of the solvent in the loose powder was 2-20%. The resulting loose powder had a bulk density of 0.25-0.464 g / cm³.3 The loose powder has both good fluffiness and adherence after makeup application, as well as a satisfactory softness. Examples 1-14 break the traditional view that the moisture in loose powder affects its fluffiness, and therefore loose powder should be dry to the point of being almost water-free. They also solve the problem that existing loose powders for cosmetics have unsatisfactory adherence due to being almost water-free.

[0091] In contrast, although Comparative Examples 1 and 2 used the same method to prepare loose powder for cosmetics, they did not control the solvent content in the dried loose powder within the range specified in this application. As a result, the prepared loose powder exhibited poor fluffiness or unsatisfactory adherence. While Comparative Example 3 controlled the solvent content in the dried loose powder within the preferred range specified in this application, it did not use vacuum freeze-drying; instead, it used conventional oven drying. This resulted in poor fluffiness in the loose powder prepared in Comparative Example 3, affecting its usability. This verifies that vacuum freeze-drying can optimize the morphology and energy transfer processes during ice crystal formation and removal in the material, having a crucial impact on the texture of loose powder, such as fluffiness.

[0092] In Examples 1-14, Examples 1-6 used liquid nitrogen tunnels to pre-freeze the material during the preparation of the loose powder for cosmetics, while Examples 7-12 used high-pressure freezing. Since the ice formed by the solvent water in the material under normal atmospheric pressure is type I ice crystal, its density is lower than that of water; however, the ice crystal formed by water under higher pressure has a higher density than liquid water, and these ice crystals are type II-VI ice crystals. The structure of type II-VI ice crystals is more complex than that of type I ice crystals. In the embodiments of this application, high-pressure freezing is a superior pre-freezing method compared to liquid nitrogen freezing. Examples 7-12, which use high-pressure freezing, cause the solvent (e.g., water) in the mixture to form more numerous and smaller type II-VI ice crystals during the freezing process. Subsequent vacuum freeze-drying removes the type II-VI ice crystals, resulting in the best possible fluffiness, adherence, and softness of the prepared loose powder.

[0093] Examples 13-14 employed a method of heating the mixture before filling, with the aim of increasing the fluidity of the mixture. However, compared to the pneumatic feeding device used in Examples 1-12, the heating step caused the mixture to undergo a process of filling heating followed by pre-freezing and cooling, which to some extent damaged the original bonding and molecular arrangement between the powder components. As a result, the evaluation results of the prepared loose powder decreased. In addition, it may also lead to the deactivation or partial deactivation of high-temperature sensitive active substances in the loose powder raw material components. Therefore, in the embodiments of this application, using a pneumatic feeding device for filling is a relatively better filling method.

[0094] The loose powder for cosmetics and its preparation method provided in this application successfully solve the current problem that loose powder for cosmetics cannot simultaneously achieve both fluffiness and adherence, thus providing a better prospect for the development and application of loose powder for cosmetics.

[0095] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A loose powder for cosmetic use, comprising at least a filler, a moisturizer, and a solvent, wherein, The loose powder for cosmetic use does not contain silylated silica; The solvent has a mass percentage content of 2-20% in the loose cosmetic powder, and the bulk density of the loose cosmetic powder is 0.250-0.464 g / cm3; In the preparation process of the loose powder for cosmetics, a vacuum freeze-drying process is used to dry the solvent in the loose powder for cosmetics.

2. The loose powder for cosmetic use according to claim 1, wherein, The solvent has a mass percentage content of 5-16% in the loose powder for cosmetics, and the bulk density of the loose powder for cosmetics is 0.263-0.456 g / cm3.

3. A loose powder for cosmetic use according to claim 2, wherein, The solvent has a mass percentage content of 8-14% in the loose powder for cosmetics, and the bulk density of the loose powder for cosmetics is 0.270-0.420 g / cm3.

4. A loose powder for cosmetic use according to claim 1, wherein, The solvent is selected from one or more of deionized water, plant extracts, and plant fermentation broth.

5. A loose powder for cosmetics according to claim 1, wherein the loose powder for cosmetics further comprises one or more of a surface modifier, a preservative, an antioxidant, a sunscreen, and an active ingredient.

6. A loose powder for cosmetic use according to claim 5, wherein, The filler is selected from one or more of the following: mica, synthetic fluorophlogopite, boron nitride, bismuth oxychloride, silica, potassium sodium aluminum silicate, lauroyl lysine, calcium aluminum borosilicate, calcium sodium borosilicate, starch and its derivatives, and plastic microspheres; and / or: The emollient is selected from at least one of the following: plant oils, silicone oils, triglycerides (ethylhexanoate), bis-diglyceride polyacryladiate-2, isononyl isononyl ester, lauryl laurate, hydrogenated polydecene, cetyl ethylhexanoate, diisostearyl malate, glycolipids, and octyl dodecyl stearyl oxystearyl ester; and / or: The surface modifier is selected from at least one of triethoxyoctylsilane, polydimethylsiloxane, hydrogenated polydimethylsiloxane, and isopropoxytitanium triisostearate; and / or: The preservative is selected from at least one of phenoxyethanol, parabens, chlorphenesin, potassium sorbate, sodium benzoate, or preservative synergists; the preservative synergist is selected from at least one of caprylyl glycol, p-hydroxyacetophenone, ethylhexylglycerin, 1,2-hexanediol, capryloyl hydroxamic acid, 1,2-pentanediol, glyceryl caprylate, and cymene; and / or: The antioxidant is selected from at least one of dipalmitoyl hydroxyproline, tocopheryl acetate, pentaerythritol tetra(bis-tert-butylhydroxyhydrocinnamate), and tocopherol; and / or: The active ingredient is selected from heat-sensitive or heat-insensitive active ingredients, wherein the heat-sensitive active ingredient is selected from at least one of polypeptide active ingredients, astaxanthin, vitamin A alcohol or its derivatives, vitamin C or its derivatives, and arbutin.

7. A loose powder for cosmetic use according to claim 5, wherein, The mass fractions of the filler, emollient, surface modifier, preservative, antioxidant, and active ingredient are as follows: filler 55-95 parts; emollient 1-20 parts; surface modifier 0.01-5 parts; preservative 0.1-2 parts; antioxidant 0.05-1 part; sunscreen 0-5 parts; and active ingredient 0-5 parts.

8. A method for preparing a loose powder for cosmetic use according to any one of claims 1-7, wherein, Includes the following steps: Mixing: Provide raw materials for preparing loose powder for cosmetic use, mix them to obtain a mixture; Filling: Filling the container with the mixture according to the preset amount; Pre-freezing: Pre-freezing the mixture in the container; Drying: The pre-frozen mixture is subjected to vacuum freeze-drying until the mass percentage content of the solvent in the cosmetic powder is reduced to the range specified, thereby obtaining the cosmetic powder.

9. A method for preparing a loose powder for cosmetic use according to claim 8, wherein, The step of filling the container with the mixture in a preset amount specifically includes: filling the container with the mixture under the action of gravity or air pressure at room temperature or under heating conditions.

10. A method for preparing a loose powder for cosmetic use according to claim 8, wherein, The pre-freezing step of the mixture in the container is performed using liquid nitrogen freezing, and the temperature of the liquid nitrogen freezing is -85 to -75°C.

11. A method for preparing a loose powder for cosmetic use according to claim 8, wherein, The pre-freezing step of the mixture in the container is carried out by high-pressure freezing, with a temperature of -20 to -40°C and a pressure of 50 to 100 MPa.

12. A method for preparing a loose powder for cosmetic use according to claim 8, wherein, The vacuum freeze-drying specifically includes the following steps: using a freeze dryer to freeze-dry the mixture that has been frozen into a solid state, and removing the solvent in the mixture into a gaseous state under vacuum to a preset content range.

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