Method for producing a slurry containing metal-doped porous silica

Abstract

To provide a manufacturing method of a slurry containing porous silica doped with a metal which makes it easy to uniformly disperse porous silica doped with metal in liquid or cream-like article and to carry on a carrier, and is excellent in handleability.SOLUTION: Using media with a bulk density of 2 to 5 g / cm3, the metal doped porous silica is wet crushed to suspend the porous silica doped with the metal having a median diameter of 0.1 to 8 μm in the dispersion medium.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for producing a slurry containing metal-doped porous silica.

Background Art

[0002] Since porous silica has a large specific surface area and pore volume, it is well known that it is used in various fields as an adsorbent, a humidity control agent, a catalyst carrier, etc. In recent years, various attempts have been made to enhance the functionality of porous silica. As one of the research results, the present inventors have reported in Patent Document 1 that porous silica doped with a metal such as copper exhibits an excellent deodorizing effect against sulfur-containing odors.

[0003] The metal-doped porous silica reported by the present inventors in Patent Document 1 is expected to be used as a material for deodorizing sulfur-containing odors remaining in hair after a perm treatment using a sulfur-containing compound such as cysteamine as a reducing agent. However, in order to exert its effect without regret, it is important how to blend the metal-doped porous silica into a perm treatment agent in a liquid or cream form. The blending of the metal-doped porous silica into the perm treatment agent may be performed by adding the metal-doped porous silica in powder form to the perm treatment agent. However, in this method, it is not always easy to uniformly disperse the metal-doped porous silica in the perm treatment agent. Further, when the metal-doped porous silica is supported on a carrier such as a fiber or a nonwoven fabric and used, it is difficult to support the metal-doped porous silica on the carrier in powder form.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Therefore, an object of the present invention is to provide a method for producing a slurry containing metal-doped porous silica, which is excellent in handleability and facilitates uniformly dispersing the metal-doped porous silica in liquid or cream-like articles or supporting it on a carrier.

Means for Solving the Problems

[0006] As a result of intensive studies in view of the above points, the present inventors have found that by wet-grinding metal-doped porous silica to a predetermined size using a medium having a predetermined bulk density, a slurry containing metal-doped porous silica with excellent handleability can be obtained.

[0007] Based on the above findings, the with a specific surface area of 600 to 1200 m 2 / g, Method for producing a slurry containing metal-doped porous silica is, as described in claim 1, a metal-doped porous silica, a dispersion medium, and Using a medium having a bulk density of 2 to 5 g / cm 3 Wet-grind the metal-doped porous silica, and suspend the metal-doped porous silica having a median diameter of 0.1 to 8 μm in a dispersion medium. (In the above, the metal-doped porous silica means a porous silica in which a metal is chemically bonded and incorporated into an inorganic network composed of siloxane bonds constituting the porous silica.) . Further, the production method according to claim 2 is the production method according to claim 1, wherein the medium is a ball mainly made of alumina having a bulk density of 2.5 to 4 g / cm 3 . Further, the production method according to claim 3 is the production method according to claim 1 or 2, wherein the metal doped in the porous silica is at least one selected from copper, aluminum, zirconium, cobalt, manganese, and iron.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a method for producing a slurry containing metal-doped porous silica, which is excellent in handleability and facilitates uniformly dispersing the metal-doped porous silica in liquid or cream-like articles or supporting it on a carrier.

Embodiments for Carrying Out the Invention

[0009] In the method for producing a slurry containing metal-doped porous silica of the present invention, the metal-doped porous silica is wet pulverized using a medium having a bulk density of 2 to 5 g / cm 3 and suspended in a dispersion medium to obtain metal-doped porous silica having a median diameter of 0.1 to 8 μm. Here, the "metal-doped porous silica" means porous silica in which a metal is chemically bonded and incorporated into an inorganic network composed of siloxane bonds constituting the porous silica. The metal-doped porous silica may be, for example, that described by the present inventors in Japanese Patent Application Laid-Open No. 2020-15640. Specifically, it is as follows.

[0010] Examples of the metal doped into the porous silica include copper, aluminum, zirconium, cobalt, manganese, and iron. These may be used alone or in combination of two or more.

[0011] The content of the metal in the metal-doped porous silica (the total amount of each when using a combination of two or more metals) is, for example, 0.01 to 10 wt%, preferably 0.1 to 5 wt%. If the content of the metal in the metal-doped porous silica is less than 0.01 wt%, the effect of doping the metal may not be sufficiently obtained. On the other hand, porous silica doped with a metal in an amount exceeding 10 wt% may be difficult to produce. When using a combination of two or more metals, the content ratio between the metals may be, for example, 0.1 to 2 times the content of one metal with respect to the content of the other metal.

[0012] Examples of the porous silica include mesoporous silica in which pores (mesopores) having a diameter of 2 to 50 nm are regularly arranged.

[0013] The specific surface area of the porous silica is preferably, for example, 500 to 2000 m 2 / g in terms of maintaining durability.

[0014] The production of the metal-doped mesoporous silica can be carried out, for example, according to the following method known per se described in JP-A-2020-15640.

[0015] (Step 1) First, a surfactant and a raw material for doping a metal into the mesoporous silica are dissolved in a solvent and stirred, for example, at 30 to 200°C for 0.5 to 10 hours to form micelles in the surfactant.

[0016] The amount of the surfactant dissolved in the solvent is, for example, 10 to 400 mmol / L, preferably 50 to 150 mmol / L. Alternatively, the amount of the surfactant dissolved in the solvent is, for example, 0.01 to 5.0 mol, preferably 0.05 to 1.0 mol, per 1 mol of the silica raw material added in Step 2 described below.

[0017] As the surfactant, any of cationic surfactants, anionic surfactants, and nonionic surfactants may be used, but preferably a cationic surfactant such as an alkylammonium salt. The alkylammonium salt preferably has an alkyl group with 8 or more carbon atoms, and more preferably has an alkyl group with 12 to 18 carbon atoms in view of easy industrial availability. Specific examples of the alkylammonium salt include hexadecyltrimethylammonium chloride, cetyltrimethylammonium bromide, stearyltrimethylammonium bromide, cetyltrimethylammonium chloride, stearyltrimethylammonium chloride, dodecyltrimethylammonium bromide, octadecyltrimethylammonium bromide, dodecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, didodecyldimethylammonium bromide, ditetradecyldimethylammonium bromide, didodecyldimethylammonium chloride, and ditetradecyldimethylammonium chloride. The surfactant may be used alone or in combination of two or more kinds.

[0018] The dissolution amount of the raw material for doping the metal into the mesoporous silica in the solvent (the total amount of each raw material when using a combination of two or more metals) is, for example, 0.001 to 0.5 mol, preferably 0.01 to 0.1 mol, per 1 mol of the silica raw material added in Step 2 described later.

[0019] As raw materials for doping metal into mesoporous silica, for example, metal nitrates, sulfates, chlorides, and oxychlorides can be used. When doping copper, it is preferable to use copper nitrate or copper chloride. When doping aluminum, it is preferable to use aluminum chloride. When doping zirconium, it is preferable to use zirconium oxychloride. When doping cobalt, it is preferable to use cobalt nitrate. When doping manganese, it is preferable to use manganese chloride. When doping iron, it is preferable to use iron chloride. The raw materials for doping metal may be used alone or in combination of two or more.

[0020] As the solvent, for example, water can be used. The solvent may be a mixed solvent of water and a water-soluble organic solvent such as methanol, ethanol, polyhydric alcohols such as diethylene glycol and glycerin.

[0021] (Step 2) Next, a silica raw material is dissolved, for example, at room temperature in the solution in which the surfactant forms micelles obtained in Step 1, and stirred until it becomes uniform to accumulate the silica raw material on the surface of the micelles of the surfactant. The amount of the silica raw material dissolved in the solution is, for example, 0.2 to 1.8 mol / L. Alternatively, when water or a mixed solvent of water and a water-soluble organic solvent is used as the solvent, it is, for example, 0.001 to 0.05 mol with respect to 1 mol of water.

[0022] The silica raw material is not particularly limited as long as it forms an inorganic network composed of siloxane bonds constituting mesoporous silica by dehydration condensation. Specific examples of the silica raw material include tetraalkoxysilanes such as tetraethoxysilane, tetramethoxysilane, and tetra-n-butoxysilane, and sodium silicate. Tetraalkoxysilane is preferable, and tetraethoxysilane is more preferable. The silica raw material may be used alone or in combination of two or more.

[0023] (Step 3) Next, the silica raw material accumulated on the surface of the surfactant micelles is dehydrated and condensed to form an inorganic network composed of siloxane bonds that make up the mesoporous silica, and a metal is chemically bonded and incorporated into the inorganic network. The dehydration condensation of the silica raw material can be carried out, for example, by adding a basic aqueous solution to the system to raise the pH and then stirring at room temperature for 1 hour or more. The basic aqueous solution is preferably added so that the pH becomes 8 - 14 immediately after addition, and more preferably 9 - 11. Specific examples of the basic aqueous solution include an aqueous sodium hydroxide solution, an aqueous sodium carbonate solution, and aqueous ammonia, but preferably an aqueous sodium hydroxide solution. The basic aqueous solution may be used alone or in combination of two or more. In addition, the dehydration condensation of the silica raw material can also be carried out by adding an acidic aqueous solution such as an aqueous hydrochloric acid solution to the system to lower the pH and then stirring.

[0024] (Step 4) Finally, the surfactant micelles having an inorganic network composed of siloxane bonds that make up the mesoporous silica and having a metal chemically bonded and incorporated on the surface, obtained in Step 3, are filtered and recovered as a precipitate, and after drying at, for example, 30 - 70°C for 10 - 48 hours, they are calcined at 400 - 600°C for 1 - 10 hours to obtain the target mesoporous silica doped with the metal.

[0025] Note that the addition of the raw material for doping the metal into the mesoporous silica into the system is not limited to the mode of dissolving in the solvent together with the surfactant in Step 1 above. As long as the formation of the inorganic network composed of siloxane bonds that make up the mesoporous silica by the dehydration condensation of the silica raw material in Step 3 is completed, it may be in the mode of dissolving in the solution in Step 2 or Step 3.

[0026] In the method for producing a slurry containing metal-doped porous silica of the present invention, stipulating that the median diameter of the metal-doped porous silica after wet grinding is 0.1 to 8 μm is because if the metal-doped porous silica is wet ground until the median diameter is less than 0.1 μm, the structure of the porous silica may be destroyed, resulting in a significant decrease in specific surface area and pore volume, and there is a risk of deterioration of its function. On the other hand, metal-doped porous silica with a median diameter exceeding 8 μm is likely to settle in the slurry and may be inferior in handleability. The upper limit of the median diameter of the metal-doped porous silica after wet grinding is preferably 5 μm, more preferably 2 μm.

[0027] In the method for producing a slurry containing metal-doped porous silica of the present invention, the bulk density of the media used for wet grinding the metal-doped porous silica is 2 to 5 g / cm 3 is stipulated because if the bulk density is less than 2 g / cm 3 , the grinding energy for the metal-doped porous silica is too weak, and it may be difficult to wet grind until the median diameter becomes 0.1 to 8 μm, or it may take an unnecessarily long time. On the other hand, if the bulk density exceeds 5 g / cm 3 , the grinding energy is too strong, and the structure of the porous silica may be destroyed, resulting in a significant decrease in specific surface area and pore volume, and there is a risk of deterioration of its function. By using a media with a bulk density of 2 to 5 g / cm 3 , a slurry containing metal-doped porous silica with a median diameter of 0.1 to 8 μm can be efficiently obtained with a high maintenance rate (percentage of the value after wet grinding with respect to the value before wet grinding) of at least 50% or more, preferably 60% or more, more preferably 70% or more of the specific surface area and pore volume.

[0028] Specific examples of the media with a bulk density of 2 to 5 g / cm 3 include those with a bulk density of 2.5 to 4 g / cm 3In addition to balls made mainly of alumina (for example, the purity of alumina is 85% or more), glass beads, zircon balls, silicon nitride balls, silicon carbide balls, etc. can be mentioned. Such media may be those with a diameter of 0.5 to 30 mmφ that are commercially available for grinding or dispersion.

[0029] Since the dispersion medium used for wet grinding becomes the dispersion medium of the slurry containing porous silica doped with metal, considering the versatility of the slurry, water, methanol, ethanol, polyhydric alcohols such as diethylene glycol and glycerin, etc. are preferable. The pH of the dispersion medium is, for example, 5 to 11, preferably 6 to 9. If the pH of the dispersion medium is less than 5, the metal doped in the porous silica may dissolve, while if the pH of the dispersion medium exceeds 11, the porous silica may dissolve.

[0030] Wet grinding of porous silica doped with metal can be carried out by putting the porous silica doped with metal and the dispersion medium in an amount such that the content of the porous silica doped with metal in the slurry is, for example, 0.1 to 20 wt%, preferably 1 to 10 wt% into a mill pot together with the media. Wet grinding of porous silica doped with metal in an amount such that the content of the porous silica doped with metal in the slurry exceeds 20 wt% may become difficult due to the increase in viscosity, while in a slurry with a content of porous silica doped with metal less than 0.1 wt%, the porous silica doped with metal may not fully exhibit its function. It is also possible to carry out wet grinding using a part of the dispersion medium necessary to make the content of the porous silica doped with metal in the slurry a predetermined content, and add the remaining dispersion medium later. The amount of media used and the grinding time vary depending on the amount of the porous silica doped with metal to be wet ground and the desired median diameter, etc. For example, 5 to 100 g of media can be used for 1 g of the porous silica doped with metal, and it can be ground for 1 to 48 hours.

[0031] Before wet - grinding the metal - doped porous silica, pre - grind the metal - doped porous silica with a mixer or the like and set its median diameter to about 10 - 40 μm, so that the wet - grinding of the metal - doped porous silica can be carried out efficiently.

[0032] The slurry containing the metal - doped porous silica produced by the method of the present invention in this way has a median diameter of the metal - doped porous silica of 0.1 - 8 μm, is excellent in handleability, and the specific surface area and pore volume are not significantly reduced by wet - grinding, so it is excellent in functionality (the specific surface area is, for example, 600 - 1200 m 2 / g and the pore volume is, for example, 0.4 - 1 cm 3 / g. The pore diameter is, for example, 2 - 50 nm). Therefore, it can be used as a functional material that facilitates uniform dispersion in liquid or cream - like articles or loading on a carrier. Specifically, for example, when copper, manganese, iron, etc., which are known as deodorant metals that can be doped into porous silica, are selected as the metals doped into the porous silica, it can be used for deodorization. Also, when copper, zirconium, cobalt, etc., which are known as bacteriostatic metals that can be doped into porous silica, are selected as the metals doped into the porous silica, it can be used for bacteriostasis.

Example

[0033] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not to be construed as limited to the following description.

[0034] Production Example 1: Production of mesoporous silica doped with copper and aluminum (Part 1) Hexadecyltrimethylammonium chloride as a surfactant, copper chloride as a raw material for doping copper into mesoporous silica, and aluminum chloride as a raw material for doping aluminum into mesoporous silica were dissolved in water as a solvent, stirred at 100 °C for 1 hour, cooled to room temperature, and then tetraethoxysilane as a silica raw material was further dissolved and stirred until homogeneous. Next, an aqueous sodium hydroxide solution as a basic aqueous solution was added to the reaction solution so that the pH immediately after addition was 9, and the mixture was stirred at room temperature for 20 hours. The generated precipitate was filtered and recovered, dried at 50 °C for 24 hours, and then calcined at 570 °C for 5 hours to obtain the target mesoporous silica doped with copper and aluminum as a slightly bluish-white powder.

[0035] Note that the respective usage amounts of hexadecyltrimethylammonium chloride as a surfactant, copper chloride as a raw material for doping copper into mesoporous silica, aluminum chloride as a raw material for doping aluminum into mesoporous silica, and water as a solvent were as follows with respect to 1 mol of tetraethoxysilane as a silica raw material. Hexadecyltrimethylammonium chloride: 0.225 mol Copper chloride: 0.0204 mol Aluminum chloride: 0.0482 mol Water: 125 mol Also, in order to prepare an aqueous sodium hydroxide solution as a basic aqueous solution, 0.195 mol of sodium hydroxide was used with respect to 1 mol of tetraethoxysilane as a silica raw material.

[0036] The mesoporous silica doped with copper and aluminum obtained by the above method has a specific surface area of 1100 m 2 / g and a pore volume of 0.72 cm 3 / g, the pore diameter was 2.6 nm (measured by the multi-point method using BELSORP MAX II manufactured by MicrotracBEL at liquid nitrogen temperature for the nitrogen gas adsorption isotherm and calculated by the BJH method). Also, approximately 50 mg of mesoporous silica doped with copper and aluminum was accurately weighed, dissolved in 4 mL of hydrochloric acid, and then the concentrations of copper and aluminum in the hydrochloric acid solution were measured using an inductively coupled plasma optical emission spectrometer (ICP-OES manufactured by Thermo Scientific). Based on the measurement results, the content of copper and the content of aluminum in the mesoporous silica doped with copper and aluminum were calculated. As a result, the content of copper was 1.85 wt% and the content of aluminum was 1.87 wt%. The doping of copper and aluminum in the mesoporous silica was confirmed by an X-ray photoelectron spectrometer (K-Alpha Surface Analysis manufactured by Thermo Scientific) and a transmission electron microscope (JEM2010 manufactured by JEOL).

[0037] The mesoporous silica doped with copper and aluminum obtained by the above method was pulverized with a mixer, and the median diameter was 27.5 μm (by a laser diffraction particle size distribution measuring device (SALD-3100 manufactured by Shimadzu Corporation), the same applies hereinafter).

[0038] Production Example 2: Production of Mesoporous Silica Doped with Copper and Aluminum (Part 2) Except that the amount of aluminum chloride used as a raw material for doping aluminum into mesoporous silica used in Production Example 1 was changed to 0.0241 mol, mesoporous silica doped with copper and aluminum was obtained as a slightly bluish white powder in the same manner as in Production Example 1, and then pulverized with a mixer to have a median diameter of 36.1 μm.

[0039] Production Example 3: Production of Mesoporous Silica Doped with Copper Except for not using aluminum chloride as a raw material for doping aluminum into mesoporous silica, which was used in Production Example 1, mesoporous silica doped with copper was obtained as a slightly bluish-white powder in the same manner as in Production Example 1, and then pulverized with a mixer to have a median diameter of 10.8 μm.

[0040] Table 1 shows the physical properties of the mesoporous silica doped with copper and aluminum or copper only obtained in Production Examples 1 to 3.

[0041]

Table 1

[0042] Example 1: Production of a slurry containing mesoporous silica doped with copper and aluminum (Part 1) In a 250 mL polypropylene pot (Iboy PP wide-mouth bottle: manufactured by AS ONE Corporation), 5 g of mesoporous silica doped with copper and aluminum obtained in Production Example 1, 95 g of water, and 210 g (about 14,000 pieces) of 2 mmφ alumina balls (manufactured by Nikkato Corporation, alumina purity: 93%, bulk density: 3.6 g / cm 3 ) were put in, and wet pulverization was carried out with a pot mill for 8 hours. Then, the alumina balls were separated by filtration to obtain a slurry with a content of 5 wt% in which mesoporous silica doped with copper and aluminum was uniformly dispersed.

[0043] Example 2: Production of a slurry containing mesoporous silica doped with copper and aluminum (Part 2) Except for using ethanol instead of water used in Example 1 and carrying out wet pulverization for 16 hours, in the same manner as in Example 1, a slurry with a content of 5 wt% in which mesoporous silica doped with copper and aluminum was uniformly dispersed was obtained.

[0044] Example 3: Production of a slurry containing mesoporous silica doped with copper and aluminum (Part 3) Except for using the mesoporous silica doped with copper and aluminum obtained in Production Example 2 instead of the mesoporous silica doped with copper and aluminum obtained in Production Example 1 used in Example 1, a slurry with a content of 5 wt% in which the mesoporous silica doped with copper and aluminum was uniformly dispersed was obtained in the same manner as in Example 1.

[0045] Example 4: Production of a slurry containing mesoporous silica doped with copper Except for using the mesoporous silica doped with copper obtained in Production Example 3 instead of the mesoporous silica doped with copper and aluminum obtained in Production Example 1 used in Example 1, a slurry with a content of 5 wt% in which the mesoporous silica doped with copper was uniformly dispersed was obtained in the same manner as in Example 1.

[0046] Example 5: Production of a slurry containing mesoporous silica doped with copper and aluminum (No. 4) Except for using 145 g (about 14,000 pieces) of 2 mmφ glass beads (manufactured by AS ONE Corporation, soda glass: 100%, bulk density: 2.5 g / cm 3 ) instead of the media used in Example 1, a slurry with a content of 5 wt% in which the mesoporous silica doped with copper and aluminum was uniformly dispersed was obtained in the same manner as in Example 1.

[0047] Example 6: Production of a slurry containing mesoporous silica doped with copper and aluminum (No. 5) Except for using 235 g (about 14,000 pieces) of 2 mmφ zircon beads (manufactured by AS ONE Corporation, zirconia: 55 - 65% and silica: 35 - 45%, bulk density: 4.0 g / cm 3 ) instead of the media used in Example 1, a slurry with a content of 5 wt% in which the mesoporous silica doped with copper and aluminum was uniformly dispersed was obtained in the same manner as in Example 1.

[0048] Comparative Example 1: Production of a slurry containing mesoporous silica doped with copper and aluminum (No. 6) Instead of the media used in Example 1, 350 g (about 14,000 pieces) of 2 mmφ zirconia balls (manufactured by Nikkato Corporation, zirconia purity: 95%, bulk density: 6.0 g / cm 3 ) were used, and wet grinding was performed for 3 hours in the same manner as in Example 1, except that a slurry with a content of 5 wt% in which mesoporous silica doped with copper and aluminum was uniformly dispersed was obtained.

[0049] Table 2 shows the adopted wet grinding conditions of the slurries containing mesoporous silica doped with copper and aluminum, or copper only, obtained in Examples 1 to 6 and Comparative Example 1, and Table 3 shows the physical properties.

[0050]

Table 2

[0051]

Table 3

[0052] As is clear from Table 3, when attempting to obtain a slurry containing porous silica doped with fine metal with a median diameter of around 0.5 μm, when wet grinding was performed using zirconia balls with a bulk density of 6.0 g / cm 3 , the grinding energy for the porous silica doped with metal was too strong, and much of the structure of the porous silica was destroyed, and the maintenance rates of the specific surface area and pore volume were less than 50%. However, when wet grinding was performed using alumina balls, glass beads, or zircon beads with a bulk density in the range of 2 to 5 g / cm 3 , the maintenance rates of the specific surface area and pore volume could be at least 50% or more.

[0053] Application Example 1: Production of a perming treatment agent containing mesoporous silica doped with copper and aluminum The slurry containing mesoporous silica doped with copper and aluminum obtained in Example 1 was added to a commercially available cream-shaped perming agent (second agent) so that the addition amount was 10 wt%, and stirred well, whereby a perming agent having a deodorizing effect and a bacteriostatic effect with a content of 0.5 wt% in which mesoporous silica doped with copper and aluminum was uniformly dispersed could be produced.

Industrial Applicability

[0054] The present invention has industrial applicability in that it can provide a method for producing a slurry containing metal-doped porous silica, which is excellent in handleability and facilitates uniformly dispersing metal-doped porous silica in liquid or cream-shaped articles or supporting it on a carrier.

Claims

1. Porous silica doped with a metal, a dispersion medium, and a bulk density of 2 to 5 g / cm ３ Using a medium with a bulk density of 2 to 5 g / cm, wet-grind the porous silica doped with a metal, and suspend the porous silica doped with a metal, having a median diameter of 0.1 to 8 μm, in a dispersion medium to produce a slurry containing the porous silica doped with a metal, having a specific surface area of 600 to 1200 m2 / g (in the above, the porous silica doped with a metal means a porous silica in which a metal is chemically bonded and incorporated into an inorganic network composed of siloxane bonds constituting the porous silica).

2. The medium is a ball mainly made of alumina with a bulk density of 2.5 to 4 g / cm ３ The production method according to claim 1, wherein the ball is made of alumina with a bulk density of 2.5 to 4 g / cm as the main material.

3. The production method according to claim 1 or 2, wherein the metal doped into the porous silica is at least one selected from copper, aluminum, zirconium, cobalt, manganese, and iron.

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