Silica manufacturing method

Abstract

To provide a silica production method which produces silica with high purity by removing impurities and can shorten production time, and cosmetics containing silica having a particle shape and size adjusted to suit the characteristics of cosmetics.SOLUTION: The method for producing silica includes a grinding step (S41) of grinding a vegetable raw material (9), a washing step (S42) of washing the vegetable raw material obtained in the grinding step with water, a dehydration step (S43) of storing the vegetable raw material in a mesh-like dehydration container 15 after the washing step and rotating it with a rotary dehydrator to remove water contained in the vegetable raw material, a firing step (S44) of firing the vegetable raw material, and a fine grinding step (S45) of finely grinding the silica obtained in the firing step.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for efficiently producing silica from plant-derived raw materials. [Background technology]

[0002] Conventionally, silica in the form of fine silicon dioxide has a lower water absorption rate than ordinary powders. Taking advantage of this, it is used in cosmetics such as eye shadow and foundation to prevent solidification due to moisture, and in creams and emulsions for stabilization purposes. Silicon dioxide has also been used as an anode material in battery materials that use high-purity silicon.

[0003] Of these types of silica, crystalline silica is known to be a harmful substance, but amorphous silica is not designated as a harmful substance and can be used in cosmetics, food (including supplements), building materials, and agricultural fertilizer and feed (for livestock and pets).

[0004] For example, Patent Document 1 describes rice husk charcoal or rice straw charcoal that is rich in amorphous silica and is carbonized using a carbonization device in which rice husks or rice straw are carbonized while being stirred in an oxygen-free atmosphere, and the temperature range at which the rice husks or rice straw are carbonized in the carbonization device is 500°C to 700°C.

[0005] Furthermore, the present invention includes a method for producing amorphous silica, which comprises stirring the rice husk charcoal or rice straw charcoal with ion-exchanged water at a temperature in the range of 30 to 100°C, and dissolving and extracting the amorphous silica contained in the rice husk charcoal or rice straw charcoal in the ion-exchanged water. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-181144 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] However, conventional manufacturing methods require the burning of organic matter such as cellulose to extract amorphous silica, but metal ions remain as impurities in plants, making it difficult to increase the purity. Furthermore, the longer the manufacturing process takes, the higher the cost becomes, so mass production is required using a manufacturing method that is as short and cost-effective as possible. In addition, there is a growing demand for silica to replace resin microbeads, and as a result, silica has been actively developed to suit the applications of cosmetics such as foundations and emulsions.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide an apparatus for producing silica with high purity or whiteness by removing impurities and capable of shortening production time, a method for producing silica, and cosmetics containing silica whose particle shape and size have been adjusted to suit the properties of the cosmetics. [Means for solving the problem]

[0009] a soaking step of soaking the plant material in an acid solution; a washing step in which the plant-derived raw material is immersed in water, agitated, and rinsed; a dehydration step in which the plant raw material is placed in a dehydration container after the soaking step and rotated by a rotary dehydrator to remove water from the plant raw material; a baking step of baking the plant-based raw material obtained from the dehydration step; The present invention is characterized by comprising: [Effects of the Invention]

[0010] The above features shorten the drying time required when immersing in a solution or washing with water, as in the past, improving production efficiency, while also promoting the decomposition of cellulose and other impurities, making it possible to remove impurities.Furthermore, it is possible to produce silica with an increased degree of pure whiteness that is ideal for use as a cosmetic material. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing a process flow illustrating the manufacturing steps for producing silica shown in Example 1 of the embodiment. [Figure 2] FIG. 2 is a diagram showing a process flow illustrating the manufacturing steps for producing silica shown in Example 2 of the embodiment. [Figure 3] FIG. 2 is a diagram showing a process flow illustrating the manufacturing steps for producing silica shown in Example 3 of the embodiment. [Figure 4] FIG. 1 is a diagram showing a process flow illustrating the manufacturing steps for producing silica shown in Example 4 of the embodiment. [Figure 5] FIG. 1 is a diagram showing a process flow illustrating the manufacturing steps for producing silica shown in Example 5 of the embodiment. [Figure 6] FIG. 2 is a distribution diagram showing the time and temperature of the manufacturing process for producing silica according to an embodiment. [Figure 7] 1 is a micrograph showing the particle size of silica according to an embodiment. [Figure 8] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 9] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 10] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 11] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 12] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 13] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 14] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 15] FIG. 1 is a schematic diagram showing test data of a cosmetic product containing silica according to an embodiment. [Figure 16] FIG. 1 is a schematic diagram showing a manufacturing apparatus for manufacturing silica according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The method for producing silica according to the present invention and the cosmetic product containing silica obtained by the method will be described in detail with reference to the drawings. Note that the embodiments and drawings described below are only examples of some of the embodiments of the present invention, and are not intended to limit the scope of the present invention, and can be modified as appropriate within the scope of the present invention.

[0013] <Plant-based raw materials> The plant-derived raw material 9, which is a biomass material for producing silica 10 in Example 1 or Example 2, will be described. The present invention produces amorphous silica, which is the final product, using food residues or discarded plant-derived raw material 9. Plants, wood, etc. are used as the plant-derived raw material 9, but using discarded plant-derived raw material 9, such as residues from harvesting plants, as the raw material makes it possible to obtain the raw material at low cost. [Table 1]

[0014] Table 1 is a list of the ingredients of plant-based raw materials 9. In Table 1, the percentages of the ingredients making up the raw material shown on the far left are shown on the right. For example, rice straw contains 37.4% carbon (C), 0.53% nitrogen (N), 0.06% phosphorus (P), 0.14% phosphoric acid (PO), 1.75% potassium (K), 2.11% potash (KO), 0.05% calcium (Ca), 0.19% magnesium (Mg), and 0.11% sodium (Na).

[0015] Here, amorphous silica can be extracted from the plant-derived silicon-containing porous plant material 9 by firing it at a low temperature (600°C or higher and 800°C or lower). Many plant materials 9 have a structure in which cells are regularly arranged along the axis, and silicic acid is deposited on the cell walls, resulting in thickened cells.

[0016] Between the rows of silicified cells are rows of compressed, narrow cells, and by removing the carbonized material after carbonization, silica with a high specific surface area can be obtained. As mentioned above, the plant-derived raw material 9 is suitable for use with a high silica content of 13% or more and 35% or less.

[0017] Examples of plant-based raw materials9 that are relatively rich in silicon are shown in Table 1. In addition to rice straw, these include wheat straw, barley straw, rice bran, rice husks, buckwheat straw, soybean straw, sweet potato vines, turnip greens, carrot leaves, corn stalks, sugarcane tops, coconut shells, barley husks, cocoa shells, cocoa pods, peanut shells, mandarin peels, red cedar sawdust, larch bark, and fallen ginkgo leaves. Alternatively, plants themselves may be used instead of residues.

[0018] For example, bamboo is a material whose cellulose consists of cellulose, hemicellulose, and lignin, and whose minerals include iron, magnesium, calcium, manganese, copper, and nickel. When bamboo or bamboo leaves are burned, silanol groups (Si-OH) are extracted, and are converted into SiO4 during the burning process.

[0019] [Table 2] [Table 3]

[0020] Tables 2 and 3 show the component composition of rice husk, the plant raw material 9 most suitable for the method of producing silica in the present invention among the plant raw materials 9 in Table 1 described above. Table 2 shows the proportions of the components constituting the raw material in percentage. For example, moisture is 8% to 10%, ash is 10% to 15%, lipids are 0.1% to 0.5%, lignin is 18% to 25%, hemicellulose is 16% to 20%, cellulose is 30% to 35%, and others are 5% to 10%. Thus, the main components of the organic matter that becomes the carbonized product are lignin, hemicellulose, and cellulose.

[0021] Table 3 shows the chemical composition of the inorganic matter in plant-based raw material 9 shown in Table 2. Plant-based raw material 9 shown in Table 2 is 80 wt% organic matter such as cellulose, and 20 wt% inorganic matter. The chemical composition of the inorganic matter in Table 3 is 92.14 wt% SiO2, 0.04 wt% Al2O3, 0.48 wt% CaO, 0.03 wt% Fe2O3, 3.2 wt% K2O, 0.16 wt% MgO, 0.18 wt% MnO, and 0.09 wt% Na2O. Plant-based raw material 9, such as rice husks shown in Table 2, contains a large amount of silicon dioxide (SiO2) in its inorganic matter.

[0022] Examples 1 to 5 of this embodiment show methods for producing silica using rice husks, which are one of the plant raw materials 9. Example 1 In Example 1, rice husks, which are one of the plant raw materials 9 of this embodiment, are used to produce silica, and a method for producing silica will be described with reference to FIG.

[0023] The plant-derived raw material 9 is pulverized (S1), but since the fine particles are produced in the fine pulverization step (S5), it is sufficient to pulverize the plant-derived raw material 9 to the extent that the particles penetrate the acid when immersed in the acid. Furthermore, since the plant-derived raw material 9 will undergo the dehydration and drying step (S3), it is sufficient that the particles are small enough not to slip through the meshes of the dehydration container 15. The optimal size after pulverization is approximately 5 to 10 mm. Examples of pulverization methods include a mill, mixer, grinder, etc.

[0024] Next, the crushed plant-based raw material 9 (S1) is immersed in an acid solution (S2). Examples of acid solutions include sulfuric acid, hydrochloric acid, citric acid, oxalic acid, malic acid, and formic acid. For example, the citric acid solution is a solution in which citric acid is dissolved in pure water at a concentration of 1% to 10% by weight (S2). After immersion for about a day, a cleaning process is performed to wash away the organic acid and eluted impurities with pure water or the like. The temperature of the aqueous organic acid solution, including citric acid, is preferably 20°C to 80°C.

[0025] Next, the plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S3). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0026] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0027] Next, in the firing step (S4), as shown in FIG. 6, the plant-derived raw material 9 is placed in a furnace, the pressure inside the furnace is brought to atmospheric pressure so that oxygen can be supplied, the temperature inside the furnace is raised to 300°C, and the temperature (a) is maintained at 300°C for a certain period of time, approximately 1 to 3 hours.

[0028] Thereafter, the furnace is made ready to supply oxygen, the temperature inside the furnace is raised to 500°C, and the temperature (b) is maintained at 500°C for a certain period of time of about 1 to 3 hours.

[0029] After that, oxygen is supplied, the temperature inside the furnace is raised to 700°C, and the temperature is maintained at 700°C for a certain period of time (c), about 1 to 3 hours. After the period of maintaining (c), the rice husks are allowed to naturally burn, and the total burning time is set to 1 day. The best burning time for (c) is 10 to 13 hours.

[0030] After that, the fire will die down naturally, and the fired silica 10 will be removed from the furnace. After the holding time (c), the rice husks will self-fire, so there is no need to use energy after the holding time (c), which reduces costs. By maintaining the temperatures of 300°C and 500°C, which require the most energy when firing rice husks, for a certain period of time, the rice husks can be completely fired, improving their purity.

[0031] The following shows an example of the composition of silica 10 after calcination. Silica (SiO2) 10 is 99.1 to 99.2%, with other components including Fe2O3 0.15 to 0.20%, Al2O3 0.05 to 0.03%, K2O 0.05 to 0.08%, CaO 0.2 to 0.5%, and MgO 0.02 to 0.065%.

[0032] Next, the silica 10 is pulverized (S5). The pulverized silica 10 has a particle size distribution ranging from 5 to 20 μm. The pulverization method may be a jet mill, a ball mill, a bead mill, or the like.

[0033] Next, melting and spheroidizing is carried out (S6). In plasma or gas thermal spraying, crushed silica powder is fed into a high-temperature flame of 2000°C or higher to melt the silica, and the molten silica, which has been spheroidized by surface tension, is then rapidly cooled to obtain spherical silica particles. Because the molten silica is rapidly cooled, the resulting spherical silica particles become amorphous.

[0034] Alternatively, the silica 10 may be spheroidized by a molten flame method, and the temperature of the flame treatment is 1750° C. to 2500° C. Alternatively, spray drying may be used as a spheroidization method. In addition, in plasma melting, a large volume of thermal plasma is generated and melted at a high temperature exceeding 10,000°C by a high frequency induction plasma method, thereby producing a spherical silica 10 powder with high sphericity. Finally, amorphous spherical silica particles 11 are produced (S7).

[0035] Example 2 In Example 2, a method for producing silica using rice husks, which are one of the plant raw materials 9 of this embodiment, will be described with reference to FIG.

[0036] The plant-derived raw material 9 is pulverized (S11), but since the fine particle size is achieved in the fine pulverization step (S15), the pulverization step is sufficient to allow the acid to penetrate the interior of the plant, and the pulverization step is sufficient to achieve a size that will not slip through the meshes of the dehydration container 15 during dehydration and drying. The optimal size after pulverization is approximately 5 to 10 mm. Pulverization methods include a mill, mixer, grinder, etc.

[0037] Next, in the firing step (S12), as shown in FIG. 6, the plant-derived raw material 9 is placed in a furnace, the pressure inside the furnace is brought to atmospheric pressure so that oxygen can be supplied, the temperature inside the furnace is raised to 300°C, and the temperature (a) is maintained at 300°C for a certain period of time, approximately 1 to 3 hours.

[0038] Thereafter, the furnace is made ready to supply oxygen, the temperature inside the furnace is raised to 500°C, and the temperature (b) is maintained at 500°C for a certain period of time of about 1 to 3 hours.

[0039] After that, oxygen is supplied, the temperature inside the furnace is raised to 700°C, and the temperature is maintained at 700°C for a certain period of time (c), about 1 to 3 hours. After the period of maintaining (c), the rice husks are allowed to naturally burn, and the total burning time is set to 1 day. The best burning time for (c) is 10 to 13 hours.

[0040] After that, the fire will die down naturally, and the fired silica 10 will be removed from the furnace. After the holding time (c), the rice husks will self-fire, so there is no need to use energy after the holding time (c), which reduces costs. By maintaining the temperatures of 300°C and 500°C, which require the most energy when firing rice husks, for a certain period of time, the rice husks can be completely fired, improving their purity.

[0041] Next, the fired silica 10 is immersed in an alkaline solution of pH 8 to 11 (S13). The alkaline solution is a solution of sodium bicarbonate, sodium percarbonate, sodium carbonate, or the like dissolved in pure water to a concentration of 1% to 10%, and the liquid temperature is preferably 20°C to 80°C, and the silica 10 is immersed in the solution for about 2 hours (S13).

[0042] Next, the calcined silica 10 is immersed in an acid solution for neutralization (S14). Examples of acid solutions include sulfuric acid, hydrochloric acid, citric acid, oxalic acid, malic acid, and formic acid. For example, the citric acid solution is a solution in which citric acid is dissolved in pure water at a concentration of 1% to 10% by weight. After immersion for about a day, a cleaning process is performed to wash away the organic acid and eluted impurities with pure water, etc. The temperature of the aqueous organic acid solution, including citric acid, is preferably 20°C to 80°C. After that, the process may be subjected to the dehydration and drying process (S3) described above.

[0043] The plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S3). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0044] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0045] Next, the silica 10 is pulverized in the same manner as in S5 described above (S15). The pulverized silica 10 has a particle size distribution ranging from 5 to 20 μm. The pulverization method may be a jet mill, a ball mill, a bead mill, or the like.

[0046] Next, melting and spheroidizing is carried out in the same manner as in S6 described above (S16). In plasma or gas thermal spraying, crushed silica powder is fed into a high-temperature flame of 2000°C or higher to melt the silica, and the molten silica, which has been spheroidized by surface tension, is then rapidly cooled to obtain spherical silica particles. Because the molten silica is rapidly cooled, the resulting spherical silica particles become amorphous.

[0047] Alternatively, the silica 10 may be spheroidized by a molten flame method, and the temperature of the flame treatment is 1750° C. to 2500° C. Alternatively, spray drying may be used as a spheroidization method.

[0048] In addition, in plasma melting, a large volume of thermal plasma is generated and melted at a high temperature exceeding 10,000°C by a high frequency induction plasma method, thereby producing spherical powder of silica 10 with high sphericity. Finally, amorphous spherical silica particles 11 are produced (S17).

[0049] Example 3 In Example 3, a method for producing silica using rice husks, which are one of the plant raw materials 9 of this embodiment, will be described with reference to FIG.

[0050] The plant-derived raw material 9 is pulverized (S21), but since the fine particle size is achieved in the fine pulverization step (S26), the pulverization step is sufficient to allow the acid to penetrate the interior of the plant-derived raw material 9 when immersed in acid. The pulverization step is also sufficient if the pulverized particles are small enough to not slip through the meshes of the dehydration container 15 during dehydration and drying. The optimal size after pulverization is approximately 5 to 10 mm. Examples of pulverization methods include a mill, mixer, grinder, etc.

[0051] Next, the steam decomposition step (S22) is a method of decomposing the pulverized plant raw material 9 by exposing it to steam. This is a step that particularly promotes the decomposition of lignin and the like, thereby improving purity and firing efficiency. The steam may be pure water or the above-mentioned citric acid solution, and a solution of 1% to 10% wt of citric acid dissolved in pure water is steamed. In the case of steam, the solution is more likely to penetrate deep into the plant-derived raw material 9, so the steam is applied for about 1 to 5 hours. After that, the above-mentioned dehydration and drying step (S3) may be carried out.

[0052] The plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S3). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0053] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0054] Next, in the firing step (S23), as shown in FIG. 6, the plant-derived raw material 9 is placed in a furnace, the pressure inside the furnace is brought to atmospheric pressure so that oxygen can be supplied, the temperature inside the furnace is raised to 300°C, and the temperature (a) is maintained at 300°C for a certain period of time, approximately 1 to 3 hours.

[0055] Thereafter, the furnace is made ready to supply oxygen, the temperature inside the furnace is raised to 500°C, and the temperature (b) is maintained at 500°C for a certain period of time of about 1 to 3 hours.

[0056] After that, oxygen is supplied, the temperature inside the furnace is raised to 700°C, and the temperature is maintained at 700°C for a certain period of time (c), about 1 to 3 hours. After the period of maintaining (c), the rice husks are allowed to naturally burn, and the total burning time is set to 1 day. The best burning time for (c) is 10 to 13 hours.

[0057] After that, the fire will die down naturally, and the fired silica 10 will be removed from the furnace. After the holding time (c), the rice husks will self-fire, so there is no need to use energy after the holding time (c), which reduces costs. By maintaining the temperatures of 300°C and 500°C, which require the most energy when firing rice husks, for a certain period of time, the rice husks can be completely fired, improving their purity.

[0058] Next, the fired silica 10 is immersed in an alkaline solution of pH 8 to 11 (S24). The alkaline solution is a solution of sodium bicarbonate, sodium percarbonate, sodium carbonate, or the like dissolved in pure water to a concentration of 1% to 10%, and the liquid temperature is preferably 20°C to 80°C, and the silica 10 is immersed in the solution for about 2 hours (S24).

[0059] Next, the silica 10 is immersed in an acid solution for neutralization (S25). Examples of acid solutions include sulfuric acid, hydrochloric acid, citric acid, oxalic acid, malic acid, and formic acid. For example, the citric acid solution is a solution in which citric acid is dissolved in pure water at a concentration of 1% to 10% by weight. After immersion for about a day, a cleaning process is performed to wash away the organic acid and eluted impurities with pure water, etc. The liquid temperature of the aqueous organic acid solution, including citric acid, is preferably 20°C to 80°C. After that, the process may be subjected to the dehydration and drying process (S3) described above.

[0060] The plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S3). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0061] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0062] Next, the silica 10 is pulverized (S26) in the same manner as in S5 described above. The pulverized silica 10 has a particle size distribution ranging from 5 to 20 μm. The pulverization method may be a jet mill, a ball mill, a bead mill, or the like.

[0063] Next, melting and spheroidizing are carried out in the same manner as in S6 (S27). In plasma or gas thermal spraying, crushed silica powder is fed into a high-temperature flame of 2000°C or higher to melt the silica, and the molten silica, which has been spheroidized by surface tension, is then rapidly cooled to obtain spherical silica particles. Because the molten silica is rapidly cooled, the resulting spherical silica particles become amorphous.

[0064] Alternatively, the silica 10 may be spheroidized by a molten flame method, and the temperature of the flame treatment is 1750° C. to 2500° C. Alternatively, spray drying may be used as a spheroidization method.

[0065] In addition, in plasma melting, a large volume of thermal plasma is generated and melted at a high temperature exceeding 10,000°C by a high frequency induction plasma method, thereby producing spherical powder of silica 10 with high sphericity. Finally, amorphous spherical silica particles 11 are produced (S28).

[0066] Example 4 In Example 4, a method for producing silica using rice husks from the plant raw material 9 of this embodiment will be described with reference to FIG.

[0067] The plant-derived raw material 9 is pulverized (S31), but since the fine particles are produced in the fine pulverization step (S38), the pulverization step is sufficient to allow the particles to penetrate the acid when immersed in the acid, and the particles should be small enough not to slip through the meshes of the dehydration container 15 during dehydration and drying. The optimal size after pulverization is approximately 5 to 10 mm. Examples of pulverization methods include a mill, mixer, grinder, etc.

[0068] Next, the crushed plant-derived raw material 9 (S31) is immersed in an acid solution (S32). Examples of acid solutions include sulfuric acid, hydrochloric acid, citric acid, oxalic acid, malic acid, and formic acid. For example, the citric acid solution is a solution in which citric acid is dissolved in pure water at a concentration of 1% to 10% by weight. After immersion for about a day, a cleaning process is performed using pure water or the like to wash away the organic acid and any eluted impurities. The temperature of the aqueous organic acid solution, including citric acid, is preferably 20°C to 80°C.

[0069] Next, the plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated using a rotary dehydration device such as a washing machine (S33). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0070] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0071] Next, in the firing step (S34), as shown in FIG. 6, the plant-derived raw material 9 is placed in a furnace, the pressure inside the furnace is brought to atmospheric pressure so that oxygen can be supplied, the temperature inside the furnace is raised to 300°C, and the temperature (a) is maintained at 300°C for a certain period of time, approximately 1 to 3 hours.

[0072] Thereafter, the furnace is made ready to supply oxygen, the temperature inside the furnace is raised to 500°C, and the temperature (b) is maintained at 500°C for a certain period of time of about 1 to 3 hours.

[0073] After that, oxygen is supplied, the temperature inside the furnace is raised to 700°C, and the temperature is maintained at 700°C for a certain period of time (c), about 1 to 3 hours. After the period of maintaining (c), the rice husks are allowed to naturally burn, and the total burning time is set to 1 day. The best burning time for (c) is 10 to 13 hours.

[0074] After that, the fire will die down naturally, and the fired silica 10 will be removed from the furnace. After the holding time (c), the rice husks will self-fire, so there is no need to use energy after the holding time (c), which reduces costs. By maintaining the temperatures of 300°C and 500°C, which require the most energy when firing rice husks, for a certain period of time, the rice husks can be completely fired, improving their purity.

[0075] Next, the fired silica 10 is immersed in an alkaline solution of pH 8 to 11 (S35). The alkaline solution is a solution of sodium bicarbonate, sodium percarbonate, sodium carbonate, or the like dissolved in pure water to a concentration of 1% to 5%, and the liquid temperature is preferably 20°C to 80°C, and the silica 10 is immersed in the solution for about 2 hours (S35).

[0076] Next, the calcined silica 10 is immersed in an acid solution for neutralization (S36). Examples of acid solutions include sulfuric acid, hydrochloric acid, citric acid, oxalic acid, malic acid, and formic acid. For example, the citric acid solution is a solution in which citric acid is dissolved in pure water at a concentration of 1% to 10% by weight. After immersion for about a day, a cleaning process is performed to wash away the organic acid and eluted impurities with pure water, etc. The temperature of the aqueous organic acid solution, including citric acid, is preferably 20°C to 80°C.

[0077] Next, the plant-derived raw material 9 soaked in acid is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S37). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0078] Dehydration removes impurities along with the water. In particular, when citric acid is used, the citric acid sequester metal ions, which are then removed together with the citric acid solution as metal chelate compounds (metal complexes). Therefore, dehydration improves the purity of the silica itself after firing. Next, drying can be done using a dryer, drying in the sun, or natural drying.

[0079] Next, the silica 10 is pulverized (S38) in the same manner as in S5 described above. The pulverized silica 10 has a particle size distribution ranging from 5 to 20 μm. The pulverization method may be a jet mill, a ball mill, a bead mill, or the like.

[0080] Next, melting and spheroidizing are carried out in the same manner as in S6 (S39). In plasma or gas thermal spraying, crushed silica powder is fed into a high-temperature flame of 2000°C or higher to melt the silica, and the molten silica, which has been spheroidized by surface tension, is rapidly cooled to obtain spherical silica particles. Because the molten silica is rapidly cooled, the resulting spherical silica particles become amorphous.

[0081] Alternatively, the silica 10 may be spheroidized by a molten flame method, and the temperature of the flame treatment is 1750° C. to 2500° C. Alternatively, spray drying may be used as a spheroidization method.

[0082] In addition, in plasma melting, a large volume of thermal plasma is generated and melted at a high temperature exceeding 10,000°C by a high frequency induction plasma method, thereby producing spherical powder of silica 10 with high sphericity. Finally, amorphous spherical silica particles 11 are produced (S40).

[0083] Example 5 In Example 5, a method for producing silica using rice husks, which are one of the plant raw materials 9 of this embodiment, will be described with reference to FIG.

[0084] The plant-derived raw material 9 is pulverized (S41), but since the fine particle size is achieved in the fine pulverization step (S45), it is sufficient to pulverize the plant-derived raw material 9 to the extent that water penetrates into the plant-derived raw material 9. Furthermore, since the plant-derived raw material 9 undergoes the dehydration step (S43), it is sufficient that the plant-derived raw material 9 is pulverized to a size that does not slip through the meshes of the dehydration container 15. The optimal size after pulverization is approximately 5 mm to 10 mm. Examples of pulverization methods include a mill, a mixer, and a grinder.

[0085] Next, the crushed plant-based raw material 9 (S41) is washed with water (S2). For example, the rice husks are soaked in pure water. After soaking the rice husks for about a day, stones, mud, etc. are washed away. The liquid temperature is preferably between room temperature and 80°C. The water washing (S2) may be performed by pouring water and then stirring. Alternatively, washing may be performed by pouring water little by little while stirring.

[0086] Next, the washed plant-derived raw material 9 is placed in a dehydration container 15 and dehydrated in a rotary dehydration device such as a washing machine (S43). The rotation speed during dehydration is preferably 300 to 3000 rpm, and most preferably 500 to 1500 rpm.

[0087] Dehydration removes impurities along with the water. It is then possible to move on to the next firing process without going through the drying process. It has been confirmed that this dehydration process by rotation also promotes the decomposition of the rice husk structure, making it possible to move on to the next process without going through the drying process. This has made it possible to reduce manufacturing time by eliminating processes.

[0088] Therefore, in Examples 1 to 4, if rotary dewatering is performed, it is not necessarily necessary to carry out a drying process, but drying will reduce the effects of corrosion on the machinery.

[0089] Next, in the firing step (S44), as shown in FIG. 6, the plant-derived raw material 9 is placed in a furnace, the pressure inside the furnace is brought to atmospheric pressure so that oxygen can be supplied, the temperature inside the furnace is raised to 300°C, and the temperature (a) is maintained at 300°C for a certain period of time, approximately 1 to 3 hours.

[0090] Thereafter, the furnace is made ready to supply oxygen, the temperature inside the furnace is raised to 500°C, and the temperature (b) is maintained at 500°C for a certain period of time of about 1 to 3 hours.

[0091] After that, oxygen is supplied, the temperature inside the furnace is raised to 700°C, and the temperature is maintained at 700°C for a certain period of time (c), about 1 to 3 hours. After the period of maintaining (c), the rice husks are allowed to naturally burn, and the total burning time is set to 1 day. The best burning time for (c) is 10 to 13 hours.

[0092] After that, the fire will die down naturally, and the fired silica 10 will be removed from the furnace. After the holding time (c), the rice husks will self-fire, so there is no need to use energy after the holding time (c), which reduces costs. By maintaining the temperatures of 300°C and 500°C, which require the most energy when firing rice husks, for a certain period of time, the rice husks can be completely fired, improving their purity.

[0093] The purity of silica 10 produced by the above manufacturing method, as determined by ICP atomic emission spectrometry, is 97.7% to 98.8%. Other typical metals contained include Ca, K, Al, Mg, Mn, Na, P, and Zn. Ca is contained at 4,700 ppm to 11,000 ppm, K at 750 ppm to 15,000 ppm, Mg at 730 ppm to 1,500 ppm, Mn at 450 ppm to 640 ppm, P at 270 ppm to 470 ppm, and Zn at 89 ppm to 110 ppm.

[0094] Next, the silica 10 is pulverized (S45) in the same manner as in S5 described above. The pulverized silica 10 has a particle size distribution ranging from 5 to 20 μm. Methods for pulverizing this silica include jet mills, ball mills, and bead mills.

[0095] Next, melting and spheroidizing are carried out in the same manner as in S6 described above (S46). In plasma or gas thermal spraying, crushed silica powder is fed into a high-temperature flame of 2000°C or higher to melt the silica, and the molten silica, which has been spheroidized by surface tension, is then rapidly cooled to obtain spherical silica particles. Because the molten silica is rapidly cooled, the resulting spherical silica particles become amorphous.

[0096] Alternatively, the silica 10 may be spheroidized by a molten flame method, and the temperature of the flame treatment is 1750° C. to 2500° C. Alternatively, spray drying may be used as a spheroidization method.

[0097] In addition, in plasma melting, a large volume of thermal plasma is generated and melted at a high temperature exceeding 10,000°C by a high frequency induction plasma method, thereby producing spherical powder of silica 10 with high sphericity. Then, in the final stage, amorphous spherical silica particles 11 are produced (S47).

[0098] Furthermore, during the acid immersion (S2), steam decomposition (S22), and water washing (S42), these processes may be carried out at a temperature of around 120°C and under pressure of 80 kPa to 150 kPa. Applying pressure has the effect of shortening the process time and accelerating the decomposition of the structure since a large amount of acid remains. This has made it possible to shorten the process time and improve the purity of the silica.

[0099] Next, a manufacturing device for firing the silica 10 (S4, S12, S23, S34, S44) will be described with reference to FIG. Fig. 16 is a schematic diagram of a mesh-type continuous firing furnace 100. Fig. 16(A) is a schematic diagram showing the internal structure of the mesh-type continuous firing furnace 100 as viewed from the side. The mesh-type continuous furnace 100 has a mesh-type conveyor belt 102 attached to rollers 107 on which a drive motor 106 and a drive belt are attached. The mesh-type continuous furnace 100 can reach temperatures from room temperature to 1000°C, and it is possible to adjust the temperature gradient, temperature retention time, etc.

[0100] In the mesh-type continuous firing furnace 100, the plant-based raw material 9 is placed into a plurality of mesh-type storage containers 110 that are transported from an entrance 101 to an exit 109. A mesh-type conveyor belt 102 transports the plurality of mesh-type storage containers 110 from the entrance 101 to the exit 109.

[0101] Since the plant-based raw material 9 generates gas when burned, the mesh-type continuous firing furnace 100 takes gas exhaust into consideration and is equipped with a waste intake port 105 inside the furnace and an exhaust port 104 for waste to the outside. This allows combustible gas to be discharged to the outside, reducing the amount of tar remaining in the furnace.

[0102] 16(B) is a plan view of the mesh-type conveyor belt 102. The mesh-type conveyor belt has a mesh-like structure that allows air to flow into the plant-based material 9, making it easier for the plant-based material 9 to burn.

[0103] 16(C) is a schematic diagram of mesh-type storage container 110. Mesh-type storage container 110 has a metal mesh (116) made of stainless steel or the like on the bottom surface of housing 114, which has a certain height, to facilitate the transfer of heat from heater 103 from both the top and bottom and to facilitate the intake of air. Mesh-type storage container 110 also has a handle 112 on the side of housing 114 to make it easy to hold.

[0104] (cosmetics) Next, a cosmetic product 20 using the silica 10 or amorphous spherical silica particles 11 produced by the production method of Examples 1 to 6 will be described with reference to Table 5 and FIGS. 7 to 15.

[0105] Figure 7 shows micrographs of silica 10 or amorphous spherical silica particles 11 produced by the production methods of Examples 1 to 5. Figures 7(A), (B), and (C) show amorphous spherical silica particles 11 (represented by the symbol LU-A10 below) having a particle size of 5 to 10 μm.

[0106] 7(A) is a photograph of the whole particle group of amorphous spherical silica particles 11. FIG. 7(B) is a photograph of the whole particle of a single amorphous spherical silica particle 11. Figure 7(C) is an enlarged photograph of a single particle of amorphous spherical silica particle 11. As can be seen in Figure 7(C), the surface has a crater-like shape, and irregular irregularities of various sizes ranging from 0.05 to 0.5 µm are formed all over the surface.

[0107] 7(D), (E), and (F) show silica 10 produced by the production methods of Examples 1 to 5, which have only undergone the fine pulverization steps (S5, S15, S26, S38, S45, and S66) prior to melt spheroidization (S6), etc. Silica 10 (represented by the symbol LU-C10 below) has a particle size of 5 to 10 μm.

[0108] FIG. 7(D) is a general photograph of a group of particles of silica 10. FIG. 7(E) is a general photograph of a single particle of silica 10. FIG. 7(F) is an enlarged photograph of a single particle of amorphous spherical silica particle 11. As can be seen in FIG. 7(D), the particles vary in shape and size. As can be seen in FIG. 7(E), the particles are block-shaped, and as can be seen in FIG. 7(F), the surface has a crater-like shape with irregular irregularities of various sizes ranging from 0.05 to 0.5 μm.

[0109] Figures 7(G), (H), and (I) show amorphous spherical silica particles 11 (represented by the symbol LU-C5 below) with a particle diameter of 5 μm or less. Figure 7(G) is a photograph of a group of amorphous spherical silica particles 11 as a whole. Figure 7(H) is a photograph of a single amorphous spherical silica particle 11 as a whole. Figure 7(H) is a magnified photograph of a single amorphous spherical silica particle 11. As can be seen in Figure 7(I), the surface has a crater-like shape, with irregularities of various sizes ranging from 0.01 to 0.1 μm formed throughout the particle.

[0110] [Table 4] Table 4 shows a table of comparative materials used when testing each of the prepared cosmetics 20. LU-A10 are amorphous spherical silica particles 11 with a particle size of 5 to 10 μm produced by the manufacturing method of Examples 1 to 5. LU-C10 are silica particles 10 with a particle size of 5 to 10 μm produced by the manufacturing method of Examples 1 to 5. LU-C5 are amorphous spherical silica particles 11 with a particle size of 5 μm or less produced by the manufacturing method of Examples 1 to 5.

[0111] SiO-15 is a comparative sample of porous, spherical mineral silica with a particle size of 15 μm. SiO-16 is a comparative sample of porous, spherical mineral silica with a particle size of 16 μm. KMP5 is a comparative sample of dense, spherical, crosslinked polymethylsilsesquioxane with a particle size of 5 μm. KSP5 is a comparative sample of dense, spherical, crosslinked vinyl dimethicone / methicone silsesquioxane with a particle size of 5 μm. KSP12 is a comparative sample of dense, spherical, crosslinked vinyl dimethicone / methicone silsesquioxane with a particle size of 12 μm.

[0112] Ny5 is a comparative sample of dense spherical polyamide particles with a diameter of 5 μm. Ny10 is a comparative sample of dense spherical polyamide particles with a diameter of 10 μm. Acl15 is a comparative sample of dense spherical cross-linked polyacrylate particles with a diameter of 15 μm. Acl30 is a comparative sample of dense spherical cross-linked acrylic polymer particles with a diameter of 30 μm. PMM8 is a comparative sample of porous spherical polymethyl methacrylate particles with a diameter of 8 μm.

[0113] TA-25 is a comparative sample of porous cellulose acetate spherical particles with a particle size of 8-10 μm. C-25 is a comparative sample of porous cellulose spherical particles with a particle size of 8-10 μm. C-25N is a comparative sample of dense cellulose spherical particles with a particle size of 8-10 μm. D-5 is a comparative sample of dense cellulose spherical particles with a particle size of 5 μm. D-10 is a comparative sample of dense cellulose spherical particles with a particle size of 10 μm. D-30 is a comparative sample of dense cellulose spherical particles with a particle size of 30 μm. TalcEX-10 is a comparative sample of talc flakes with a particle size of 15 μm. MicaY-1800 is a comparative sample of mica flakes with a particle size of 10 μm. PDM-5L is a comparative sample of synthetic mica flakes with a particle size of 6 μm.

[0114] Next, we will explain how to prepare test samples using the above sample. The above sample was mixed with a commercially available foundation in a ratio of 2:18 to create a dry sample. Additionally, to add oil, the above sample was mixed with olive oil in a ratio of 2:18 to create an oil-added sample. The oils added are not limited to olive oil, but also include jojoba oil, argan oil, rosehip oil, horse oil, sesame oil, macadamia nut oil, avocado oil, coconut oil, marula oil, etc.

[0115] Figure 8A shows the whiteness. The white bars in the graph show the L* values ​​measured on the colorimeter when the above-mentioned dry sample was applied to the surface of the artificial leather. The solid bars show the L* values ​​measured on the colorimeter when the above-mentioned oil-added sample was applied to the surface of the artificial leather. The L* value is scaled from 0 (black) to 100 (white), with larger values ​​indicating greater whiteness. The larger the value, the greater the hiding power, and the smaller the value, the greater the sense of transparency.

number

[0116] FIG. 8B shows saturation. C* shows the numerical value calculated by the formula shown in Equation 1. a* shows the change in color from red to green, and b* shows the change in color from blue to yellow. These numerical values ​​were measured using a color difference meter.

[0117] The white bars in the graph show the C* values ​​when the dry sample was applied to the artificial leather surface. The solid bars show the C* values ​​when the oil-added sample was applied to the artificial leather surface. The larger the C* value, the greater the hiding power, and the smaller the value, the greater the transparency.

[0118] Figure 9 shows the L* and C* values ​​shown in Figure 8, obtained by dividing the oiled sample by the dry sample. The white bars in the graph show the L* values. The solid bars show the C* values. The closer the value is to 1, the greater the effect of preventing the influence of wetting due to sebum. LU-C10 is close to 1.0, so it is highly effective in preventing the influence of wetting due to sebum. From the above results, LU-C10 is evaluated as having high covering power and high resistance to wetting by sebum.

[0119] Figure 10 shows the evaluation of uniform dispersion by applying the foundation prepared using the above method to a sponge applied to an artificial leather sheet and evaluating the color variation. The smaller the standard deviation α, the more uniform the color. The white bars in the graph indicate the L* values. The solid bars indicate the C* values. From these results, it was confirmed that LU-C10 and LU-C5 have small variations.

[0120] Figure 11A shows the degree of lightness measured for each bulk density. The open bars in the graph show the powder values ​​for the dry sample. The solid bars show the powder values ​​for the oil-added sample. LU-C10 was confirmed to have a low bulk density and be light.

[0121] Figure 11B shows the coefficient of kinetic friction (MIU) measured by moving a sponge back and forth on the surface of the foundation created using the above-mentioned method. The white bars in the graph show the values ​​for the powder of the dry sample. The solid bars show the values ​​for the powder of the oil-added sample. LU-C10 was confirmed to have a low coefficient of kinetic friction. The smaller this value, the lighter the product is and the smoother it spreads.

[0122] Figure 12 shows the drying speed test. A certain amount of the foundation prepared above was applied to the artificial leather-covered rice cake substrate, which was made by covering a piece of rice cake with oil blotting paper and then taping artificial leather on top of that, and the drying speed was measured at room temperature. The values ​​shown are for the dry sample. The solid bars show the values ​​for the oil-added sample. It was confirmed that LU-C10 had a slow drying speed. The smaller this value, the greater the moisturizing effect.

[0123] Next, we will show the test of blending emulsion. 10 mL of emulsion was dispensed into a test tube, and 0.2% of each of the above comparative powder samples was added and stirred to create an emulsion. Figure 13A shows a drying rate test similar to that described above for a comparative sample formulated with emulsion. It was confirmed that U-C10 has a slow drying rate. The smaller this value, the higher the moisturizing effect.

[0124] Figure 13B shows a test in which a certain amount of a comparative sample containing emulsion was added to an artificial leather-coated rice cake substrate and the contact angle was measured using a digital microscope. LU-C5 was confirmed to have a low water droplet contact angle. A low contact angle indicates high wettability. The contact angle of LU-C5 was between 30 degrees and 40 degrees. Figure 13C shows the measured coefficient of dynamic friction (MIU) of the comparative sample containing the emulsion as described above. It was confirmed that LU-C5 had a large coefficient of dynamic friction.

[0125] As described above, blending LU-C5 and LU-C10 into emulsions results in a slower drying rate and enhanced moisturizing effects. Blending porous powders generally enhances moisture evaporation, but the amorphous spherical silica particles 11 produced in this example, with a diameter of 5 μm or less, have a low contact angle, enhancing hydrophilicity and retaining moisture. Furthermore, because the moisture retention capacity remains high even after 24 hours, the surface has a high coefficient of kinetic friction (MIU).

[0126] Next, in the case of tests using a liquid foundation, 0.2% of the above comparative powder samples was added to 10 mL of liquid foundation dispensed into a test tube, and the mixture was stirred to prepare a liquid foundation.

[0127] Figure 14A shows the values ​​measured with a color difference meter after applying the liquid foundation to the surface of artificial leather. a* indicates a solid black bar graph, showing a change in color from red to green. b* indicates a solid light gray bar graph, showing a change in color from blue to yellow. Small a* and b* values ​​indicate a sense of transparency. LU-C10 shows a relatively small value.

[0128] Figure 14B shows the L* values ​​measured with a colorimeter after applying the above liquid foundation to the surface of artificial leather. A smaller L* value indicates a more transparent look. LU-C10 shows a relatively small value.

[0129] 15A shows the values ​​measured with a gloss meter when the liquid foundation was applied to the surface of artificial leather. LU-A10, LU-C10, and LU-C5 had relatively small gloss values, but suppressed shine. 15B shows the values ​​measured for color unevenness when the liquid foundation was applied to the surface of artificial leather and measured with a color difference meter. LU-C10 had a particularly small standard deviation, indicating high uniformity of dispersion.

[0130] Formulated with LU-C10, it has an extremely slow drying speed, high moisturizing effect, low color unevenness, low MIU, and a high contact angle, so it spreads smoothly and forms a uniform oily film, providing high moisturizing power, and low L*, a*, and b* for a transparent look. It also has a low gloss, resulting in a natural transparency with reduced shine and greasiness.

[0131] (Technical features) Below, examples of the technical features of this embodiment are shown in parentheses, but they are not particularly limiting and are merely examples, and the effects that can be expected from these features will also be described.

[0132] The method is characterized by including a grinding step (e.g., a grinding step (S41) of mainly plant-based raw materials) for grinding plant-based raw materials (e.g., mainly plant-based raw materials 9 (rice husks, etc.)), a washing step (e.g., a mainly water-washing step (S42)) for washing the plant-based raw materials obtained in the grinding step with water, a dehydration step (e.g., mainly a dehydration step (S43)) for storing the plant-based raw materials after the washing step and rotating them in a rotary dehydrator to remove water contained in the plant-based raw materials, a firing step (e.g., mainly a firing step (S44)) for firing the plant-based raw materials, and a fine grinding step (e.g., mainly a grinding step (S45)) for finely grinding the silica obtained in the firing step. In addition to washing with water, immersing the material in an acid solution and then dehydrating it will further promote decomposition and shorten the drying time.

[0133] The above features reduce the time required for drying after immersion in a solution or washing with water, as was previously the case, improving production efficiency while also accelerating the decomposition of cellulose and other substances, making it possible to remove impurities.

[0134] <Feature 2> The rotation speed of the rotating device is 300 rpm to 3000 rpm.

[0135] The above features reduce the time required for drying after immersion in a solution or washing with water, as was previously the case, improving production efficiency while also accelerating the decomposition of cellulose and other substances, making it possible to remove impurities.

[0136] <Feature 3> The firing step is characterized by including the steps of: making the furnace capable of supplying oxygen; increasing the temperature in the furnace to 300°C; maintaining the temperature at 300°C for a certain period of time; increasing the temperature in the furnace to 500°C; maintaining the temperature at 500°C for a certain period of time; increasing the temperature in the furnace to 700°C; maintaining the temperature at 700°C for a certain period of time; and then firing the plant-based raw material by natural firing.

[0137] The above features allow for efficient combustion by setting a certain time at two temperature ranges where gas is most likely to be released and calories are consumed when burning cellulose, etc. Furthermore, after maintaining a certain time at two stages, the plant-based ingredients are allowed to burn naturally, making it possible to burn without consuming energy.

[0138] <Feature 4> The method is characterized by including a steam decomposition step (for example, mainly the steam decomposition step (S22)) that promotes decomposition of the plant-derived raw material by steam before the burning step.

[0139] The above-mentioned features facilitate the decomposition of cellulose and other materials, making it possible to burn them efficiently.

[0140] <Feature 5> The silica particles are amorphous spherical silica particles obtained by spheroidizing silica that has been pulverized to 5 to 10 mm in the pulverization step of a silica manufacturing method, and are characterized by the addition of silica that has a particle diameter of 5 μm or less, an irregular block shape, and irregular irregularities of 0.01 to 0.1 μm formed on the surface.

[0141] The above features make it possible to provide cosmetics that have a relatively low gloss value and can suppress shine.

[0142] <Feature 6> The silica is characterized by the addition of a group of silica particles having an irregular block shape and a particle size of 5 to 10 μm, which are obtained by the pulverization step of the silica manufacturing method, and having irregularly uneven surfaces on the silica surface.

[0143] The above features make it possible to provide cosmetics that have an extremely slow drying speed, high moisturizing effect, low color unevenness, and a high contact angle, which allows it to spread smoothly and form a uniform oily film, resulting in high moisturizing power, and low L*, a*, and b*, which gives it a transparent feel.It also has a low gloss, so it is possible to provide cosmetics that have a natural transparency with reduced shine and greasiness.

[0144] <Feature 7> It is characterized by the addition of silica that creates irregular irregularities of 0.05 μm to 0.5 μm on the crater-like surface.

[0145] The above features make it possible to provide cosmetics that have an extremely slow drying speed, high moisturizing effect, little color unevenness, and a high contact angle, which allows it to spread smoothly and form a uniform oily film, resulting in high moisturizing power and transparency. It also has a low gloss, reducing shine and greasiness, and provides a natural transparency.

[0146] <Feature 8> A plurality of storage containers (e.g., mainly mesh-type storage containers 110) having a metal mesh bottom on which the plant-based raw materials are placed; a continuous furnace (e.g., mesh-type continuous firing furnace 100) equipped with a metal mesh-shaped conveyor belt (e.g., mainly a mesh-type conveyor belt 102) for conveying the container; heater units (e.g., mainly heater 103) for burning the plant-based raw material, located above and below the conveyor belt; The continuous furnace is characterized by being provided with an exhaust port (for example, mainly the exhaust port 104) for discharging gases generated during combustion in the furnace from the furnace to the outside.

[0147] The above features make it possible to provide a silica production bed that can continuously burn a large amount of plant-based raw materials over a long period of time. In addition, by using a mesh-like conveyor belt and storage container, air is sent to the plant-based raw materials, making them easier to burn. [Explanation of symbols]

[0148] 9 Plant-based raw materials 10 Silica 11. Amorphous spherical silica particles 100 mesh continuous firing furnace 102 Mesh conveyor belt 103 Heater 104 Exhaust port 110 Mesh storage container S41 Crushing process of plant-based raw materials S43 Dehydration process S44 Firing process S45 Grinding process.

Claims

1. A grinding step of grinding the plant raw material; a soaking step of soaking the pulverized plant material in an acid solution; a dehydration step in which the plant-derived raw material is placed in a container after the soaking step and rotated in a rotary dehydrator to remove water from the plant-derived raw material; a baking step in which the plant-based raw material is baked while still undried after the dehydration step; a finely pulverizing step of finely pulverizing the silica obtained in the calcination step; a melt-spheroidizing step of melting and spheroidizing the silica obtained by the pulverizing step; A method for producing silica, comprising:

2. A grinding step of grinding the plant raw material; a water washing step of washing the pulverized plant raw material with water; a dehydration step in which the plant-derived raw material is placed in a container after the water washing step and rotated in a rotary dehydrator to remove water from the plant-derived raw material; a baking step in which the plant-based raw material is baked while still undried after the dehydration step; a finely pulverizing step of finely pulverizing the silica obtained in the calcination step; a melt-spheroidizing step of melting and spheroidizing the silica obtained by the pulverizing step; A method for producing silica, comprising:

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