Manufacturing method for SiO2-containing hardened material

Abstract

To provide a concrete substitute without using a cement which generate much carbon dioxide during manufacturing process.SOLUTION: A manufacturing method of a SiO2-containing hardened body is a manufacturing method which includes a) a step of blending a SiO2-containing raw material, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound, b) a step of forming a SiO2-containing hardened body by heat treatment of a blend obtained in the step of a), and c) a step of separating the SiO2-containing hardened body formed in the step of b).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for efficiently obtaining a hardened body from SiO2-containing materials such as sand and gravel. [Background technology]

[0002] Concrete is the most widely used construction material in the world. Cement is used as the main ingredient in concrete, but there is a problem in that a large amount of carbon dioxide is emitted during its production. In addition, the recoverable life of limestone, the main ingredient in cement, is estimated to be at least several decades in Japan, and at most a hundred and several decades. As the recoverable life is similar in other countries that produce concrete in large quantities, such as China, India, and the United States, there is a limit to how much can be achieved by importing.

[0003] For this reason, the development of a construction material that does not use cement to replace concrete has become an urgent issue (for example, Patent Document 1, etc.). Requirements for an alternative material include an almost unlimited supply of raw materials and the ability to be reused. In this regard, the most abundant materials on earth are sand and gravel, which contain silicon as a main component, and if construction materials could be produced directly from these, they would be considered to be effective concrete alternatives. However, at present, concrete alternatives that are practical enough have not yet been realized. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-6610 A Summary of the Invention [Problem to be solved by the invention]

[0005] Therefore, an object of the present invention is to provide a concrete substitute that does not use cement, which emits a large amount of carbon dioxide during the manufacturing process. [Means for solving the problem]

[0006] As a result of intensive research aimed at solving the above problems, the inventors have discovered that by subjecting SiO2-containing materials, such as sand and gravel, to high-temperature treatment in an alcohol compound and an alkali metal compound or an alkaline earth metal compound, it is possible to efficiently obtain a hardened body in which the SiO2-containing materials are directly bonded to each other, and have completed the present invention.

[0007] That is, in one aspect, the present invention provides <1> A method for producing a SiO2-containing hardened material, comprising: a) a step of mixing a raw material containing SiO2, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound; b) a step of heat-treating the mixture obtained in step a) to produce a SiO2-containing hardened material; and c) a step of separating the SiO2-containing hardened material produced in step b); <2> The SiO2-containing raw material is 1 to 50 parts by weight based on 100 parts by weight of the alcohol compound. <1> 2. The method of claim 1 , <3> The alkali metal compound or alkaline earth metal compound is 1 to 20 parts by weight per 100 parts by weight of the raw material containing SiO2. <1> or <2> 2. The method of claim 1 , <4> The heat treatment in step b) is carried out at a temperature of 100 to 300°C. <1> ~ <3> 10. The method for producing a semiconductor device according to claim 9, <5> The raw material containing SiO2 has a particle shape with a particle size in the range of 1 μm to 10 cm. <1> ~ <4> 10. The method for producing a semiconductor device according to claim 9, <6> The SiO2-containing raw material includes silica stone, silica sand, diatomaceous earth, quartz, or silica. <1> ~ <5> 10. The method for producing a semiconductor device according to claim 9, <7> The SiO2-containing raw material is gravel or sand. <1> ~ <6> 10. The method for producing a semiconductor device according to claim 9, <8> The alcohol compound is ethanol or methanol. <1> ~ <7> 10. The method for producing a semiconductor device according to claim 9, <9> The alkali metal compound is at least one selected from the group consisting of hydroxides, halides, sulfates, carbonates, and hydrogen carbonates of alkali metals. <1> ~ <8> 10. The method for producing a semiconductor device according to claim 9, <10> The method according to claim 1, further comprising adding a basic solution or an aprotic organic solvent in the step a). <1> ~ <9> 10. The method for producing a semiconductor device according to claim 9, <11> The method further comprises pressing solid components in the mixture in step b). <1> ~ <10> 10. The method for producing a semiconductor device according to claim 9, <12> The above method includes subjecting the SiO2-containing hardened body separated in the step c) to a heat drying treatment. <1> ~ <11> The manufacturing method according to any one of the above This provides:

[0008] In another aspect, the present invention also relates to a method and agent for treating SiO2-containing materials, specifically, <13> A method for treating a SiO2-containing material, comprising: A) a step of mixing a SiO2-containing material, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound; and B) a step of heat-treating the mixture obtained in step A; <14> The SiO2-containing material is gravel or sand having a particle size in the range of 1 μm to 10 cm. <13> 2. The processing method according to claim 1 ; <15> A treatment agent for SiO2-containing materials, comprising an alcohol compound and an alkali metal compound or an alkaline earth metal compound; and <16> The SiO2-containing material is gravel or sand having a particle size in the range of 1 μm to 10 cm. <15> The treatment agent according to Regarding. Effect of the Invention

[0009] According to the present invention, a hardened body in which SiO2-containing materials are directly bonded to each other can be obtained without using cement, which emits a large amount of carbon dioxide during the manufacturing process, and a new concrete substitute can be provided efficiently at low cost. The hardened body of the present invention can use a wide range of SiO2-containing materials such as sand and gravel as raw materials, which are materials that are available almost infinitely on Earth, so there is no need to worry about shortages. Furthermore, since sand and gravel are easily available on the surface of the moon and Mars, they are expected to be used in space development.

[0010] Furthermore, since the hardened body of the present invention is hardened without using conventional cement paste, it has the following advantages, for example. - Small volume change due to drying and wetting; · Small creep change; - Suppresses deterioration caused by calcium leaching due to water or acid; - Deterioration caused by alkali-aggregate reaction (expansion of aggregate in an alkaline environment) can be suppressed; - The time required for strength development can be shortened (compared to about one month for ordinary concrete, this invention allows for strength development in about 24 hours); The alkali metal compounds used in the manufacturing process are catalysts and can be reused repeatedly. The alcohol compounds used in the manufacturing process can be recycled after high-temperature treatment. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is an image showing the pressure reaction vessel used in the examples. [Diagram 2] FIG. 2 is an image of the cured product of the present invention obtained in the example. [Diagram 3] Figure 3 shows an image of the hardened specimen obtained after heating for 24 hours in 13.8% KOH / silica (6 g silica sand; 0.83 g KOH). [Figure 4] Figure 4 shows an image of the hardened specimen obtained after heating for 24 hours in 16.5% KOH / silica (6 g silica sand; 1 g KOH). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present invention will be described. The scope of the present invention is not limited to these descriptions, and other than the following examples, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention.

[0013] 1. Method for producing the cured product of the present invention The manufacturing method of the present invention is for producing a hardened body of a SiO2-containing material, and is characterized by including the following steps a) to c). a) mixing a raw material containing SiO2, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound; b) heat-treating the mixture obtained in step a) to produce a SiO2-containing hardened material; and c) A step of separating the hardened SiO2-containing material produced in step b).

[0014] Although not necessarily bound by theory, the mechanism by which a SiO2-containing hardened body is obtained in the manufacturing method of the present invention is presumed to be as follows. Fukaya et al. have reported that tetraalkoxysilane, an organosilicon compound, can be obtained by decomposing and dehydrating sand (SiO2-containing material) with alcohol (Chemistry Letters 2016 45:7, 828-830). This reaction is represented by the following reaction formula (1).

number

[0015] In the paper by Fukaya et al., the reaction product water (H2O) is removed to shift the equilibrium of the reaction equation to the right, and tetraalkoxysilane (Si(OR)4) is efficiently produced. Here, since formula (1) is a reversible equilibrium reaction, it can be interpreted that the chemical bonds of SiO2 are repeatedly broken and regenerated in the reaction. In the present invention, focusing on this point, the above reaction formula (1) is applied to an SiO2-containing material, and after tetraalkoxysilane is once produced, SiO2 on the left side is regenerated, whereby the SiO2 components present on the surface of the SiO2-containing material are bonded to each other, and an aggregate (hardened body) in which SiO2-containing materials are directly bonded to each other is obtained.

[0016] From another perspective, it is known that SiO2 produces porous silica through a sol-gel reaction. In the present invention, it is also possible to consider that only the surfaces of SiO2-containing materials are converted into a sol, thereby producing a hardened material in which SiO2-containing materials are bonded together.

[0017] In this way, the manufacturing method of the present invention utilizes the fact that the SiO2 component in the SiO2-containing material repeatedly cuts and regenerates the chemical bonds of SiO2 according to the above reaction formula, and has been characterized in that it has been discovered that a hardened body can be obtained in which SiO2-containing materials are directly bonded to each other, and that such a hardened body can actually be obtained.

[0018] In the present invention, the term "SiO2-containing material (or raw material containing SiO2)" is not particularly limited as long as it is a material containing a certain amount of SiO2, but may be a material containing natural minerals such as silica stone, silica sand, diatomaceous earth, and quartz, calcined ash of silicon-containing plants, volcanic ash, silicate salts, silica sol-derived silica gel, fumed silica, silica alumina, zeolite, glass, and other artificial materials. Preferably, silica stone, silica sand, diatomaceous earth, quartz, silica, or a combination of one or more of these materials may be included. For example, granite, rhyolite, etc. may also be included. From the viewpoint of availability, the SiO2-containing material is typically gravel or sand. Such gravel or sand may be used as aggregate when producing concrete or mortar.

[0019] In addition, the raw material containing SiO2 (SiO2-containing material) used in the present invention is preferably one having a particulate shape or an approximately particulate shape from the viewpoint of efficiency during the curing reaction. The particle size (average particle size) can be in the range of 1μ to 10 cm, preferably in the range of 10μ to 5 cm, and more preferably in the range of 100μm to 3 cm. However, as described above, the SiO2-containing material does not need to be in a perfect particulate shape, and may be in a non-uniform shape like so-called sand or gravel, so the "particle size" here should be understood to represent an approximate size.

[0020] As described above, step a) in the manufacturing method of the present invention is a step of mixing a SiO2-containing material, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound, thereby obtaining a chemical equilibrium state as shown in the above reaction formula (1).

[0021] The alcohol compound used in step a) may be an alcohol having a linear or branched alkyl, and the alkyl portion may be substituted with any substituent. The alcohol compound may be preferably an alcohol having 1 to 10 carbon atoms, and more preferably an alcohol having 1 to 5 carbon atoms. Typically, the alcohol compound is methanol or ethanol. The alcohol compound may be a raw material for obtaining the alkoxysilane on the right side of the above reaction formula (1), but may return to the alcohol on the left side again in the overall equilibrium reaction.

[0022] The alkali metal compound or alkaline earth metal compound used in step a) is a component that promotes the cleavage of the silicon-oxygen bond in SiO2 and functions as a catalyst for the production of alkoxysilane on the right side of the above reaction formula (1).

[0023] Examples of the alkali metal and alkaline earth metal in the alkali metal compound and alkaline earth metal compound include lithium (Li), sodium (Na), magnesium (Mg), potassium (K), calcium (Ca), and cesium (Cs). Examples of the counter anion include hydroxides, halides, oxides, carbonates, hydrogencarbonates, alkoxides, silicates, aluminates, phosphates, organic acid salts, sulfates, and nitrates. Among these, hydroxides, halides, carbonates, and hydrogencarbonates are preferred, and alkali metal hydroxides, alkali metal halides, alkali metal carbonates, and alkali metal hydrogencarbonates are more preferred.

[0024] Specific examples of the alkali metal compound and alkaline earth metal compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, sodium fluoride, potassium fluoride, cesium fluoride, etc. The alkali metal compound and alkaline earth metal compound may be used alone or in combination of two or more.

[0025] The alkali metal compound may preferably be at least one selected from the group consisting of hydroxides, halides, sulfates, carbonates, and hydrogen carbonates of alkali metals.

[0026] The amount of the SiO2-containing material added in step a) can be appropriately set, but is preferably 1 to 50 parts by weight, more preferably 1 to 15 parts by weight, relative to 100 parts by weight of the alcohol compound.

[0027] Moreover, the amount of the alkali metal compound or alkaline earth metal compound added in step a) is preferably 1 to 20 parts by weight, more preferably 13 to 20 parts by weight, based on 100 parts by weight of the raw material containing SiO2.

[0028] In a preferred embodiment, in step a), in addition to the alcohol compound, a basic solution or an aprotic organic solvent can be further added as a solvent. Examples of such a basic solution include aqueous ammonia, and examples of the aprotic organic solvent include acetals such as dimethoxypropane. Other ethers can also be used.

[0029] As described above, in the step b) in the manufacturing method of the present invention, the mixture obtained in the step a) is heat-treated to generate a SiO2-containing hardened material. After the reaction is performed in a high-temperature environment, the SiO2 component on the left side of the above reaction formula (1) is regenerated by cooling to room temperature, and a hardened material in which SiO2-containing materials are directly bonded to each other can be obtained.

[0030] The heating temperature in step b) is preferably in the range of 100 to 300° C., more preferably in the range of 150 to 250° C. The heating time can be appropriately set depending on the amount of reactants, etc., but is typically in the range of 12 to 96 hours, more preferably in the range of 24 to 72 hours. Cooling after heating is preferably performed by allowing to cool to about room temperature.

[0031] The reactor and operation procedure for carrying out steps a) and b) are not particularly limited and can be appropriately selected depending on the purpose. The reactor is preferably a pressure-resistant and heat-resistant reactor such as an autoclave.

[0032] The reaction pressure in steps a) and b) is not particularly limited, but is usually 0.1 MPa or more, preferably 0.5 MPa or more, more preferably 1.0 MPa or more, and is usually 60 MPa or less, preferably 30 MPa or less, more preferably 20 MPa or less.

[0033] In a preferred embodiment, step b) may further include pressing the solid components in the mixture. This can increase the strength of the SiO2-containing hardened body. The pressing is preferably a physical press, that is, a mechanical stress is applied to compress the mixture. Therefore, the reactor may be provided with a means for pressing in the reactor. As such a pressing means, for example, a metal plate having punch holes that can be driven in the vertical direction is placed in the reactor, and the solid components in the mixture are pressed by this. In this case, the dimensions of the metal plate may be slightly smaller than the inner diameter of the reactor, so that the liquid components in the mixture escape to the top through the gap with the reactor wall, and pressure can be applied only to the solid components.

[0034] Step c) in the manufacturing method of the present invention is a step of separating the SiO2-containing hardened body produced in step b) from the solvent and isolating the hardened body as the target product. For such separation, a method known in the technical field, such as filtration, can be used. The alcohol compound and the alkali metal compound or alkaline earth metal compound separated from the hardened body can be reused in the next reaction process.

[0035] In a preferred embodiment, the SiO2-containing cured product separated in step c) can be further subjected to a heat drying treatment, which can convert the hydrogen bonds on the surface of the cured product into covalent bonds through a dehydration (condensation) reaction, and is suitable for the purpose of further increasing the strength of the cured product.

[0036] 2. Treatment method and treatment agent of the present invention The manufacturing method of the present invention for obtaining a hardened body from a SiO2-containing material has been described above, but from another perspective, such a process can also be considered as a method for treating a SiO2-containing material.

[0037] That is, in another aspect, the present invention also relates to a method for treating an SiO2-containing material, comprising the following steps A) and B): A) mixing a SiO2-containing material, an alcohol compound, and an alkali metal compound or an alkaline earth metal compound; and B) A step of heat treating the mixture obtained in step A).

[0038] Here, the types and amounts of the SiO2-containing material, alcohol compound, alkali metal compound, or alkaline earth metal compound in step A) have already been described. The heating conditions in step B) are also similarly described above. In a preferred embodiment, the SiO2-containing material to be treated by the present invention is gravel or sand having a particle size in the range of 1 μm to 10 cm.

[0039] The present invention also relates to a treatment agent for SiO2-containing materials, which contains an alcohol compound and an alkali metal compound or an alkaline earth metal compound. The above explanation can be applied to the types and contents of the alcohol compound, alkali metal compound, or alkaline earth metal compound in the treatment agent. The SiO2-containing material to be treated with the treatment agent is preferably gravel or sand having a particle size in the range of 1 μm to 10 cm. EXAMPLES

[0040] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0041] 1.SiO 2 Manufacturing of hardened materials containing ingredients 6 g of silica sand with a particle size of 0.1 mm ("Mikawa-made silica sand No. 8" manufactured by Marutosha Co., Ltd.), 1 g of potassium hydroxide (KOH), 75 ml of ethanol, and 0.9 ml of dimethoxypropane were placed in a small box-shaped container made of thin copper or stainless steel membrane, and then placed in a pressure reactor. After sealing the reactor, it was heated at 240°C for 24 hours. After heating, the reactor was cooled to room temperature, and the obtained hardened body was isolated by filtration. The pressure inside the reactor was maintained at 5 MPa.

[0042] The reaction vessel used is shown in Figure 1. An image of the obtained cured body is shown in Figure 2.

[0043] The same reaction was carried out by varying the heating time and the amount of KOH added (w / w). The results are shown in Table 1. [Table 1]

[0044] The hardened material obtained by heating for 24 hours with 13.8% KOH / silica (6 g silica sand; 0.83 g KOH) is shown in Figure 3. Also, the hardened material obtained by heating for 24 hours with 16.5% KOH / silica (6 g silica sand; 1 g KOH) is shown in Figure 4.

[0045] Furthermore, experiments were also carried out under various other conditions to examine their effects on the formation of the hardened body.

[0046] 2. The ratio of silica sand to ethanol The ratio of silica sand to ethanol (w / w) was changed in the range of 5.1 to 20.5%, and the hardened bodies were synthesized. In each case, 50 ml of ethanol was used, 0.15 ml of dimethoxypropane was used, and KOH was 16.5% KOH / silica. The results are shown in Table 2. [Table 2]

[0047] 3. Ratio of dimethoxypropane to ethanol The ratio (w / w) of dimethoxypropane and ethanol was changed in the range of 0.06 to 0.24%, and the hardened body was synthesized. In each condition, the amount of ethanol was 75 ml, and the mass ratio of silica sand to dimethoxypropane was fixed at 42%. The results are shown in Table 3. [Table 3]

[0048] 4. Ratio of dimethoxypropane and silica sand The ratio (w / w) of dimethoxypropane and silica sand was changed in the range of 8 to 44%, and the hardened body was synthesized. In each condition, the amount of ethanol was fixed at 75 ml, the amount of KOH was fixed at 0.66 g, and the amount of silica sand was fixed at 4 g. The results are shown in Table 4. [Table 4]

[0049] 5. Heating temperature The heating temperature was changed in the range of 180 to 243, and the hardened body was synthesized. In each condition, the amount of ethanol was fixed at 75 ml, KOH at 0.66 g, silica sand at 4 g, and dimethoxypropane at 0.6 ml. The results are shown in Table 5. [Table 5]

Claims

1. SiO ２ A method for producing a hardened material containing a) SiO ２ mixing a raw material containing the above, an alcohol compound, and an alkali metal compound; b) Heat treatment of the mixture obtained in step a) to obtain SiO ２ A step of producing a hardened material of the content (excluding a step including a treatment of removing water from the mixture obtained in step a) using a molecular sieve or an organic dehydrating agent); and c) SiO produced in step b) ２ Step of separating the hardened content Including, In the step a), the alkali metal compound is ２ 13 to 20 parts by weight per 100 parts by weight of the raw material containing the alkali metal compound is potassium hydroxide, sodium hydroxide, sodium carbonate, or potassium carbonate; The SiO ２ The hardened material is formed by dissolving the SiO 2 present on the surface of the raw material containing the SiO 2 . ２ The components are bonded to each other, and the SiO 2 -containing raw materials are directly bonded to each other to form an aggregate. The manufacturing method.

2. The SiO ２ The method according to claim 1, wherein the raw material containing the above is 1 to 50 parts by weight per 100 parts by weight of the alcohol compound.

3. The method according to claim 1 or 2, wherein the heat treatment in step b) is carried out in the range of 100 to 300° C.

4. The SiO ２ The method according to any one of claims 1 to 3, wherein the raw material containing has a particle shape with a particle size in the range of 1 μm to 10 cm.

5. The SiO ２ The method according to any one of claims 1 to 4, wherein the raw material containing the compound includes silica stone, silica sand, diatomaceous earth, quartz, or silica.

6. The SiO ２ The method according to any one of claims 1 to 5, wherein the raw material containing is gravel or sand.

7. The method according to any one of claims 1 to 6, wherein the alcohol compound is ethanol or methanol.

8. The method according to any one of claims 1 to 7, further comprising adding a basic solution or an aprotic organic solvent in the step a).

9. The method according to any one of claims 1 to 8, further comprising pressing solid components in the mixture by mechanical stress in step b).

10. The SiO separated in step c) ２ The method according to any one of claims 1 to 9, further comprising subjecting the hardened material to a heat drying treatment.

11. SiO according to any one of claims 1 to 10 ２ A composition for use in a method for producing a hardened material comprising the steps of: (a) applying a cured material to a substrate to form a cured product;

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