Curing agent, kit for preparing two-component mixed hydraulic composition, two-component mixed hydraulic composition and method for producing the same, and cured product and method for producing the same

Abstract

To provide a two-component mixed hydraulic composition for 3D printers that makes it possible to stably yield a cured product with high compressive strength, and a curing agent suitably employed for preparing the two-component mixed hydraulic composition.SOLUTION: A two-component mixed hydraulic composition for 3D printers is prepared by mixing a first slurry containing a main material comprising cement, silica fume, and a retarder together with water, and a second slurry containing a curing agent and water. The curing agent contains alum, a basic aluminum salt, silica fume, and an alkali metal sulfate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a hardener, a two-component hydraulic composition preparation kit, a hydraulic composition and a method for producing the same, and a cured product and a method for producing the same. [Background technology]

[0002] Additive manufacturing methods are known in which materials such as resins, metals, and ceramics are layered on top of each other based on three-dimensional data of a desired object. A known additive manufacturing method is a material extrusion method in which a building material is extruded from the nozzle of a 3D printer and layered on top of each other. In recent years, studies have been conducted to create laminates using two-component curable compositions containing a main material containing a hydraulic binder and a hardener in separate states. For example, Patent Document 1 proposes a technique for preparing a hydraulic composition that has a good balance of mixability, layerability, rapid hardening properties, and strength development properties by mixing a main material containing a hydraulic binder with a hardener containing alum and a basic aluminum salt. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-98085 Summary of the Invention [Problem to be solved by the invention]

[0004] When a hardener contains alum as an accelerator, the setting start time is accelerated when mixed with a base material containing a binder, improving hardening properties, but the mixability of the base material and hardener tends to decrease. In this case, mixability is unlikely to be a problem when mixing using a power-driven dynamic mixer such as a Hobart mixer, but when mixing using a static mixer, the decrease in mixability is likely to be a problem. If mixability decreases, there is a concern that the strength of the hardened product will decrease.

[0005] The present disclosure provides a two-part hydraulic composition for 3D printers that can stably produce a cured product with high compressive strength, a method for producing the same, and a two-part hydraulic composition preparation kit that can smoothly prepare such a two-part hydraulic composition.The present disclosure also provides a hardener that is suitably used for preparing such a two-part hydraulic composition and two-part hydraulic composition preparation kit, and a cured product with high compressive strength. [Means for solving the problem]

[0006] One aspect of the present disclosure provides a hardening agent for use in a two-component hydraulic composition for a 3D printer, the hardening agent including alum, a basic aluminum salt, silica fume, and an alkali metal sulfate.

[0007] One way to improve the mixing property when preparing a two-component hydraulic composition for 3D printers is to reduce the amount of accelerator used. However, if the amount of alum used, which functions as an accelerator, is reduced, the amount of sulfate ions (SO4 2- ) decreases, which may result in a decrease in hardening property and a decrease in the strength of the hardened product. On the other hand, the hardener contains alkali metal sulfate. Therefore, even if the amount of alum is reduced, the alkali metal sulfate will instead convert the sulfate ions (SO4 2- It is believed that the hardener functions as a supply source of alum and alkali metal sulfate, thereby maintaining hardening properties. In this way, since the hardener contains an alkali metal sulfate as well as alum, it is possible to achieve both mixability and hardening properties when preparing a two-part hydraulic composition for 3D printers, and it is believed that a hardened product with high compressive strength can be stably obtained.

[0008] One aspect of the present disclosure provides a two-component hydraulic composition preparation kit for a 3D printer, which includes a main material or a first slurry containing the main material, and a hardening material or a second slurry containing the main material, in a separated state, wherein the main material includes cement, silica fume, and a retarder, and the hardening material is the above-mentioned hardening material.

[0009] The two-component hydraulic composition preparation kit includes a main material or a first slurry containing the main material, and a second slurry containing the hardening material, which are separated from each other. With such a two-component hydraulic composition preparation kit, a two-component hydraulic composition for 3D printers that can stably produce a hardened product having high compressive strength can be smoothly prepared at the construction site.

[0010] One aspect of the present disclosure provides a two-part hydraulic composition for 3D printers, obtained by mixing a first slurry containing a main material including cement, silica fume, and a retarder, and water, with a second slurry containing the hardener and water. Such a two-part hydraulic composition can achieve both mixability and hardening properties, and therefore can stably produce a hardened product with high compressive strength.

[0011] One aspect of the present disclosure provides a cured product obtained by curing the two-part hydraulic composition, which has high compressive strength because it is obtained by curing the two-part hydraulic composition that can achieve both mixability and curability.

[0012] One aspect of the present disclosure provides a method for producing a two-part hydraulic composition for 3D printers, comprising the step of mixing a first slurry containing water and a main material including cement, silica fume, and a retarder with a second slurry containing the hardener and water. The two-part hydraulic composition obtained by this production method uses the second slurry containing the hardener, and can achieve both mixability and hardening when mixed with the first slurry, making it possible to stably produce a hardened product with high compressive strength.

[0013] One aspect of the present disclosure provides a method for producing a cured product, comprising the steps of discharging the two-component hydraulic composition obtained by the above-mentioned production method from a discharge unit of a 3D printer, laminating the laminate, and curing the laminate to obtain a cured product. This production method uses a two-component hydraulic composition that can be both easily mixed and easily cured, and therefore can stably produce a cured product with high compressive strength. [Effects of the Invention]

[0014] According to the present disclosure, it is possible to provide a two-part hydraulic composition for 3D printers that can stably produce a hardened product having high compressive strength, a method for producing the same, and a two-part hydraulic composition preparation kit that can smoothly prepare such a two-part hydraulic composition. Furthermore, it is possible to provide a hardener that is suitably used for preparing such a two-part hydraulic composition and a two-part hydraulic composition preparation kit, and a hardened product having high compressive strength. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram illustrating an example of a construction system. [Figure 2] FIG. 1 is an exploded perspective view showing an example of a static mixer. [Figure 3] 1 is a graph showing the relationship between the content of alkali metal sulfate in the hardener relative to 100 parts by mass of the total amount of binders contained in the main material and the compressive strength of the hardened product. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present disclosure are described below. However, the following embodiments are merely examples for explaining the present disclosure and are not intended to limit the present disclosure to the following content. In the description, the same reference numerals are used for identical elements or elements having the same functions, and redundant explanations are omitted where appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships based on the orientation of the reference numerals shown in the drawings. The dimensional ratios of each element are not limited to those shown. Numerical ranges exemplified as "a to b" are numerical ranges inclusive of a and b, with a lower limit being a and an upper limit being b. The present disclosure also includes cases in which the upper or lower limit of each numerical range is replaced with the numerical value of any of the examples. When multiple materials are exemplified, one of the materials may be used alone, or multiple materials may be used in combination.

[0017] The "two-component hydraulic composition" in this disclosure is a fluid slurry containing a main material including a binder and a hardening agent that hardens the main material. The binder has the property of hardening upon reacting with water, and constitutes at least a part of a hardened product after hardening. While the "two-component hydraulic composition" has fluidity, a hydraulic composition that has lost its fluidity as it hardens is called a "hardened product." The "3D printer" in this disclosure is a device that ejects a two-component hydraulic composition from an ejection port to form a physical three-dimensional object.

[0018] The hardener is used to prepare a two-component hydraulic composition for 3D printers. The hardener contains at least alum, a basic aluminum salt, silica fume, and an alkali metal sulfate. The hardener may be in a solid form such as a powder, or may be a slurry containing water (hardener slurry).

[0019] Alum is a double salt of a sulfate of a monovalent cation and a sulfate of a trivalent metal ion. The alum contained in the hardener acts as an accelerator. Examples of alum include potassium alum, ammonium alum, sodium alum, iron alum, chromium alum, and their anhydrides (calcined alum). One of these alums may be used alone, or a combination of two or more may be used. From the viewpoint of obtaining a two-component hydraulic composition that can achieve sufficiently high levels of mixability and hardening properties, it is preferable that the alum contains potassium alum. Potassium alum is KAl(SO4)2· 12 It is a double salt of potassium sulfate and aluminum sulfate, with the chemical formula H2O.

[0020] Commercially available alum may be used, or the commercially available alum may be pulverized using a ball mill or the like. By reducing the particle size of the alum to a certain extent, the effect of the quick-setting agent can be more easily exerted while maintaining ease of handling. This allows the alum content in the hardener to be reduced. From this perspective, the average particle size of the alum may be 0.01 to 1.0 mm, 0.02 to 0.3 mm, 0.03 to 0.2 mm, or 0.04 to 0.1 mm.

[0021] The average particle size in this disclosure is determined from a volume-based frequency distribution measured using a laser diffraction / scattering particle size distribution analyzer. Measurements are performed under dry conditions using, for example, a laser diffraction / scattering particle size distribution analyzer, such as the "SALD-2200" manufactured by Shimadzu Corporation. The average particle size is calculated as a weighted average of the logarithmic values ​​of particle sizes, with the volume-based frequency for that particle size being used as the weight, based on the relationship between the volume-based frequency and the particle size obtained in the above measurement.

[0022] The content of alum in the hardener relative to the total solid content of the hardener may be 1% by mass or more, 1.5% by mass or more, or 2% by mass or more. By including a sufficient amount of alum in the hardener, the hardening property of a two-component hydraulic composition can be sufficiently increased when the composition is prepared. The content of alum in the hardener relative to the total solid content of the hardener may be 12% by mass or less, 10% by mass or less, 8% by mass or less, or 7% by mass or less. By preventing the alum content in the hardener from becoming excessive, the mixability and fluidity of a two-component hydraulic composition can be sufficiently improved when the composition is prepared. An example of the range of the content of alum in the hardener relative to the total solid content of the hardener is 1 to 12% by mass.

[0023] The hardener contains alum and a basic aluminum salt as a component that hardens the binder. The basic aluminum salt is a component also known as a gelling agent. The basic aluminum salt is a basic salt containing aluminum ions and hydroxy acid ions having 2 to 6 carbon atoms. Here, the basic salt is a hydroxide ion (OH -It is a salt containing (). In other words, the basic aluminum salt is one in which part of the anion in the salt of aluminum and hydroxy acid is replaced with hydroxide ions. The basic aluminum salt has the general formula: Al(OH) 3-x Y b It can be represented by. Here, x and b are selected so that the basic aluminum salt is electrically neutral as a whole. By using the basic aluminum salt, the formation of flocs can be suppressed, and thus the miscibility can be particularly improved.

[0024] The number of carbon atoms of the hydroxy acid ions contained in the basic aluminum salt is preferably 2 to 4, more preferably 2 or 3, and even more preferably 3. Examples of the basic aluminum salt include basic aluminum lactate, basic aluminum hydroxyacetate, basic aluminum citrate, basic aluminum tartrate, etc., and basic aluminum lactate is preferred. These may be hydrates. The basic aluminum salt may be used alone or in combination of two or more.

[0025] Basic aluminum lactate has the general formula Al(OH) 3-x (Lac.acid) x (0 < x < 3), and the molar ratio of Al2O3 / lactic acid may be 0.3 to 2.0. Lac.acid is a lactate ion. Basic aluminum lactate may be a hydrate. Examples of commercially available basic aluminum lactate include "Taxeram M-160P" (manufactured by Takaki Chemical Co., Ltd.). The content of the basic aluminum salt in the cured material with respect to the total solid content of the cured material may be 0.7 to 6.0% by mass, 1.0 to 4.5% by mass, or 1.5 to 3.5% by mass.

[0026] The cured material contains an alkali metal sulfate. The alkali metal sulfate can be a source of sulfate ions (SO4 2- ). Therefore, in the cured material, sulfate ions (SO4 2-Even if the content of alum to supply the saturation agent is insufficient, the inclusion of an alkali metal sulfate in the hardener allows the two-component hydraulic composition to have both good mixability and good hardening properties, and a hardened product with high compressive strength can be stably obtained. The alkali metal sulfate may be water-soluble. However, the "total solids content of the hardener" in this disclosure also includes the mass of the alkali metal sulfate.

[0027] The alkali metal sulfate preferably contains at least one selected from the group consisting of potassium sulfate, sodium sulfate, and lithium sulfate, and more preferably sodium sulfate, from the viewpoint of achieving both sufficiently high levels of mixability and hardening properties of the two-component hydraulic composition. The content of the alkali metal sulfate in the hardener relative to the total solid content of the hardener may be 0.5% by mass or more, 1% by mass or more, or 2% by mass or more, from the viewpoint of stably obtaining a hardened product having sufficiently high compressive strength. The content of the alkali metal sulfate in the hardener relative to the total solid content of the hardener may be 10% by mass or less, 8% by mass or less, or 6% by mass or less, from the viewpoint of suppressing an increase in the discharge pressure of a liquid pump when preparing a two-component hydraulic composition in a slurry form. An example of the content of the alkali metal sulfate in the hardener relative to the total solid content of the hardener is 0.5 to 10% by mass.

[0028] Examples of silica fume include those specified in JIS A 6207:2016 "Silica fume for concrete." The content of silica fume in the hardener relative to the total solid content of the hardener may be 2 to 20 mass%, 4 to 15 mass%, or 5 to 10 mass%. This can further improve the mixability of the hardener and the main component, and the hardening property of the two-component hydraulic composition obtained by mixing them.

[0029] The hardening material may contain metakaolin. Metakaolin contains SiO2 and Al2O3. Therefore, when the alum content is insufficient, metakaolin can be used to harden the cement. 3+This can be a supply source of Al2O3. Therefore, by including metakaolin, the two-component hydraulic composition can achieve both the mixability and hardening properties at a higher level, and a hardened product with higher compressive strength can be stably obtained. The content of Al2O3 in the metakaolin may be 43% by mass or more, or 45% by mass or more. By using metakaolin with such a high content of Al2O3, the amount of alum can be further reduced, and the two-component hydraulic composition can achieve both the mixability and hardening properties at a higher level. The content of metakaolin in the hardener relative to the total solid content of the hardener may be 5 to 30% by mass, 10 to 25% by mass, or 15 to 20% by mass. The average particle size of the metakaolin may be 0.3 to 2 μm, or 0.5 to 1.5 μm.

[0030] Since metakaolin contains SiO2, when the hardener contains metakaolin, the content of silica fume may be reduced. This allows the above-mentioned effects of metakaolin to be fully enjoyed. The total content of silica fume and metakaolin in the hardener relative to the total solid content of the hardener may be 10 to 40 mass%, 15 to 35 mass%, or 20 to 30 mass%. This allows for a sufficiently high level of both mixability and hardenability. From the same perspective, the content of metakaolin in the hardener may be higher than the content of silica fume. The ratio of silica fume to the total of silica fume and metakaolin in the hardener may be 50 mass% or less, 5 to 45 mass%, 10 to 40 mass%, or 15 to 35 mass%. This further improves the mixability of the first slurry containing the main material and the second slurry containing the hardener, sufficiently suppressing sagging when the two-component hydraulic composition is layered. Furthermore, the compressive strength of the hardened product can be sufficiently increased.

[0031] The hardener may contain components other than those described above. Examples of other components include aggregate, fly ash, silica powder, water, antifoaming agents, thickeners, water-reducing agents, and fibers. The aggregate may include fine aggregate, such as concrete aggregates specified in JIS A 5308:2019, silica sand used in building materials, and the like. The particle size of the aggregate is preferably less than 1 mm, more preferably less than 0.5 mm, from the viewpoint of pumpability when formed into a slurry. The particle size of the aggregate can be measured using several sieves with different mesh sizes specified in JIS Z 8801-1:2019. The content of the aggregate in the hardener relative to the total solid content of the hardener may be 40 to 85 mass%, 50 to 80 mass%, 55 to 75 mass%, or 60 to 70 mass%.

[0032] The fly ash may be, for example, that specified in JIS A 6201:2015 "Fly ash for concrete." The antifoaming agent, thickener, and water-reducing agent may be the same as those contained in the main material described below. Known silica powder, water, and fibers may be used.

[0033] The curing agent may be mixed with water to form a slurry (second slurry). The solid content of the second slurry may be 60 to 90 mass % or 70 to 85 mass %. By forming the curing agent into a slurry form, the mixability can be improved. In the second slurry, at least a portion of the alkali metal sulfate may be dissolved in water.

[0034] A two-component hydraulic composition for 3D printers can be obtained by mixing a first slurry containing a main material with a second slurry containing a hardening material. The components of the hardening material are as described above. The main material contains a binder (hydraulic binder) and hardens when mixed with the hardening material. The main material includes cement, silica fume, and a retarder. Examples of cement include various Portland cements such as ordinary Portland cement, early-strength Portland cement, ultra-early-strength Portland cement, moderate-heat Portland cement, low-heat Portland cement, and sulfate-resistant Portland cement, as well as various blended cements such as blast-furnace cement and fly ash cement. Only one of these cements may be used, or multiple types may be mixed and used. Among these, from the viewpoint of improving the hardening characteristics of the two-component hydraulic composition, it is preferable to include at least one Portland cement selected from the group consisting of ordinary Portland cement, early-strength Portland cement, and ultra-early-strength Portland cement.

[0035] The silica fume may be the same as that contained in the hardening agent, for example, that specified in JIS A 6207:2016 "Silica fume for concrete." The main material may contain a binder other than cement and silica fume. Examples of such binders include ground granulated blast furnace slag (for example, one conforming to JIS A 6206:2013 "Ground granulated blast furnace slag for concrete"), ground limestone, fly ash, and gypsum. The Blaine specific surface area of ​​ground granulated blast furnace slag is 2500 to 10000 cm. 2 / g, 3000-9000cm 2 / g, or 4000 to 8000 cm 2 / g. Examples of fly ash include those specified in JIS A 6201:2015 "Fly ash for concrete." Examples of gypsum include gypsum dihydrate (CaSO4·2H2O), gypsum hemihydrate (CaSO4·1 / 2H2O), and anhydrous gypsum.

[0036] The retarder is not particularly limited, and examples thereof include hydroxycarboxylic acids, sugars, and inorganic retarders. The retarder may include hydroxycarboxylic acids. The hydroxycarboxylic acids are a general term for hydroxycarboxylic acids and their salts. Examples of hydroxycarboxylic acids include gluconic acid, tartaric acid, citric acid, malic acid, succinic acid, and heptonic acid.

[0037] Examples of the salt of hydroxycarboxylic acid include alkali metal salts (sodium salt, potassium salt, etc.) and alkaline earth metal salts (calcium salt, magnesium salt, etc.). Of these, sodium salts and sodium gluconate may be included in view of the setting retardation effect, availability, and cost. The hydroxycarboxylic acid and its salt may be used alone or in combination of two or more.

[0038] The content of the retarder in the main material may be 0.05 to 1.5 parts by mass, 0.1 to 1.0 parts by mass, or 0.15 to 0.5 parts by mass relative to 100 parts by mass of the total amount of binder in the main material. By setting the content of the retarder within the above range, a suitable fluidity retention time (usable life) can be obtained.

[0039] The main material may contain at least one selected from the group consisting of a water-reducing agent, a thickener, an antifoaming agent, and an aggregate. The water-reducing agent can improve the liquid transportability when a first slurry containing the main material and water is prepared. Examples of the water-reducing agent include polycarboxylic acid-based water-reducing agents. Specific examples of polycarboxylic acid-based water-reducing agents include polyether-polycarboxylic acid-based water-reducing agents and modified polycarboxylic acid-based water-reducing agents. One of these may be used alone, or two or more may be used in combination. The content of the water-reducing agent in the main material relative to 100 parts by mass of the total amount of binder in the main material may be 0.05 to 1.0 parts by mass, 0.05 to 0.7 parts by mass, or 0.1 to 0.5 parts by mass. By setting the content of the water-reducing agent within the above range, the liquid transportability can be further improved.

[0040] The thickener can sufficiently suppress material separation when preparing a first slurry containing a main material and water. Examples of thickeners include organic thickeners such as cellulose-based thickeners, starch-based thickeners, guar gum-based thickeners, and vinyl-based thickeners, as well as inorganic thickeners such as bentonite, kaolinite, and talc. One of these may be used alone, or two or more may be used in combination. The content of the thickener in the main material relative to 100 parts by mass of the total amount of binders in the main material may be 0.01 to 1.0 parts by mass, 0.02 to 0.5 parts by mass, or 0.04 to 0.3 parts by mass.

[0041] The defoaming agent can improve the strength development of the cured product of the two-component hydraulic composition. Known defoaming agents can be used. Specific examples of defoaming agents include synthetic substances such as mineral oil-based, silicone-based, alcohol-based, and polyether-based substances, as well as natural substances derived from plants. Among these, from the viewpoints of dispersibility and durability, the defoaming agent may be a polyether-based defoaming agent or a mineral oil-based defoaming agent. One of these may be used alone, or two or more may be used in combination. The content of the defoaming agent in the main material relative to 100 parts by mass of the total amount of binder in the main material may be 0.01 to 1.0 parts by mass, 0.05 to 0.7 parts by mass, or 0.1 to 0.4 parts by mass.

[0042] The aggregate may include fine aggregate, similar to the aggregate contained in the hardening agent, and may include silica sand used in concrete aggregates and building materials, as specified in JIS A 5308:2019, etc. The particle size of the aggregate is preferably less than 1 mm, more preferably less than 0.5 mm, from the viewpoint of pumpability when made into a slurry. The particle size of the aggregate can be measured using several sieves with different mesh sizes as specified in JIS Z 8801-1:2019. The content of the aggregate in the main material relative to 100 parts by mass of the total amount of binder in the main material may be 40 to 250 parts by mass, 60 to 200 parts by mass, more preferably 80 to 150 parts by mass.

[0043] The components contained in the main material are not limited to those described above, and may include, for example, various admixtures such as an expanding agent. The main material does not need to include alum or other quick-setting agents, basic aluminum salts or other gelling agents, metakaolin, or alkali metal sulfates.

[0044] A first slurry may be prepared by mixing a main material with water. The solid content of the first slurry may be 70 to 95 mass %, or 80 to 90 mass %. By making the main material into a slurry, mixability can be improved. From the same viewpoint, the content of water in the first slurry relative to 100 mass parts of the total amount of binders in the main material may be 20 to 50 mass parts, 25 to 45 mass parts, or 30 to 40 mass parts.

[0045] The two-component hydraulic composition may be a mixed slurry obtained by mixing a first slurry containing a main material with a second slurry containing a hardening agent. The fluidity of the first slurry, the second slurry, and the mixed slurry can be evaluated by the flow test described in "JIS R 5201:2015 Physical Testing Methods for Cement." The flow value of each slurry after 15 drops may be 140 mm or more, 150 mm or more, or 170 mm or more. The flow value of each slurry can be adjusted by, for example, adjusting the ratio of water to solids (binder), the ratio of aggregate, the content of a water-reducing agent, etc.

[0046] A two-component hydraulic composition and the hardened product obtained by hardening the composition may be prepared using a 3D printer as shown in Fig. 1. The 3D printer in Fig. 1 includes a first supply unit 10 that supplies a first slurry containing a base material and water, a second supply unit 20 that supplies a second slurry containing a hardener and water, a confluence unit 30 that joins the first slurry and the second slurry, a mixing unit 40 that mixes the joined slurries produced in the confluence unit 30, a flow path 32 that connects the confluence unit 30 and the mixing unit 40, a discharge unit 60 provided downstream of the mixing unit 40, and a position adjustment unit 70 that adjusts the position of the material discharged from the discharge unit 60.

[0047] The first supply unit 10 includes a first storage unit 12 that stores a first slurry, and a first liquid feed pump 14. The second supply unit 20 includes a second storage unit 22 that stores a second slurry, and a second liquid feed pump 24. The first slurry and the second slurry stored in the first storage unit 12 and the second storage unit 22 each include the above-mentioned main material and the above-mentioned hardening material. The first storage unit 12 and the second storage unit 22 may be a transportable container, a tank truck, or a tank installed on the ground.

[0048] Various pumps can be used as the first liquid feed pump 14 and the second liquid feed pump 24. Of these, the first liquid feed pump 14 and the second liquid feed pump 24 are preferably non-pulsating pumps, and more preferably non-pulsating metering pumps. This allows the mixing ratio of the first slurry and the second slurry to be stably constant. This therefore allows the quality of the extruded product, the laminate, and the cured product (modeled object) to be sufficiently high.

[0049] The first slurry and the second slurry sent from the first storage section 12 and the second storage section 22 by the first liquid feed pump 14 and the second liquid feed pump 24 join at the confluence section 30 to form a joined slurry. The first slurry and the second slurry may be mixed so that the ratio of the hardener to the main material is 15 to 40 mass % or 20 to 35 mass %. The joined slurry produced at the confluence section 30 is introduced into the mixing section 40.

[0050] From the viewpoint of further improving workability, it is preferable that the mixing section 40 has an inline mixer, and from the viewpoint of simplifying the equipment and reducing weight, it is more preferable that it has a static mixer. A static mixer is a mixer that does not have a driving part, and is also called a static mixer or static mixer. Because a static mixer does not have a driving part, it is lightweight and can simplify the structure of the construction system. This makes it easy to handle at the construction site and further improves workability.

[0051] On the other hand, static mixers tend to have poorer mixing properties than dynamic mixers such as Hobart mixers, which can lead to sagging of the laminate and a decrease in the strength of the cured product. However, because the hardener contained in the second slurry has excellent mixing properties, even when a static mixer is used, it is possible to suppress the decrease in mixing properties, and to sufficiently suppress the occurrence of sagging of the laminate and the decrease in curing properties. Therefore, even when a static mixer is used, a two-component hydraulic composition that is easy to apply and has excellent strength development can be stably prepared.

[0052] By making the mixing section 40 a static mixer, it can be attached to the position adjustment section 70 as shown in Fig. 1 and move smoothly together with the discharge section 60. This allows the length from the confluence section 30 to the discharge section 60 to be sufficiently short, thereby reducing the amount of mixed slurry (two-component mixed hydraulic composition) remaining in the flow path 32. This allows sufficient reduction in material loss that occurs when the compositions of the first and second slurries are changed or construction is suspended.

[0053] Fig. 2 is an exploded view showing an example of a static mixer. The static mixer 40 shown in Fig. 2 has a cylindrical body 45 and an element 41 provided inside the cylindrical body 45. The element 41 is integrally formed and configured so that the element 41 can be inserted into and removed from the cylindrical body 45 along the central axis CL. When the joined slurry is introduced into the static mixer 40, it is repeatedly divided and joined by the element 41 fixed inside the static mixer 40. In this way, the joined slurry is mixed, and a mixed slurry (two-part mixed hydraulic composition) is obtained.

[0054] The static mixer is not limited to the example shown in FIG. 2, and any mixer capable of mixing the main material and hardener contained in the first slurry and the second slurry by a mixing principle such as swirling, dividing, inverting, or recombining can be used without particular limitations. The element may be configured by a series of repeating units having the same shape arranged along the central axis of a cylinder. The repeating unit of the element may have flow holes through which the slurry flows, as in static mixer 40 shown in FIG. 2. This prevents clogging of the mixed slurry, sufficiently reduces pressure loss in the static mixer, and ensures a sufficient discharge rate.

[0055] Returning to FIG. 1, the mixed slurry obtained in the mixing section 40 is discharged from the discharge section 60 and layered. A hardened product (a shaped object) can be obtained by hardening the layered product 80 thus formed. The discharge section 60 may be, for example, a nozzle. The hardened product may be a hardened mortar product. The position of the discharge section 60 is adjusted by the position adjustment section 70. Therefore, hardened products having various shapes can be obtained. The hardened product is not particularly limited, and examples thereof include buildings and structures. Examples thereof include secondary concrete products, buried formwork, buildings and benches installed in parks or campsites, etc.

[0056] The mixing section 40 may be movable together with the discharge section 60 by a position adjustment section 70 that adjusts the discharge position of the mixed slurry. This shortens the distance between the mixing section 40 and the discharge section 60, making it possible to sufficiently reduce the loss of mixed slurry that occurs at the end of construction. The position adjustment section 70, which moves the mixing section 40 and the discharge section 60 to adjust the discharge position of the mixed slurry, may be, for example, a robot arm or a gantry crane. This allows for smooth production of the laminate 80 and the hardened product even if they are large.

[0057] The 3D printer of FIG. 1 mixes the first and second slurries in the mixing section 40 and then quickly discharges the mixed slurry from the discharge section 60 to produce the laminate 80 and its hardened product. This prevents the mixed slurry from being stored for long periods of time and prevents excess mixed slurry from being produced. Furthermore, the mixed slurry discharged from the discharge section 60 has a sufficiently high mixing uniformity and excellent strength development, which effectively prevents sagging of the laminate 80 and allows for a hardened product with excellent aesthetics. Furthermore, this hardened product has high compressive strength and can be suitably used for a variety of applications. The two-component hydraulic composition obtained by mixing the first and second slurries in this way is easy to apply and reduces the burden of on-site work.

[0058] The method for producing a two-component hydraulic composition (mixed slurry) for a 3D printer and the method for producing a hardened product may be performed using the 3D printer of Fig. 1. In the method for producing a two-component hydraulic composition (mixed slurry), the mixing step of mixing a first slurry containing a main material and water with a second slurry containing a hardener and water may be performed using a static mixer 40. In the method for producing a hardened product, the two-component hydraulic composition obtained by the above-mentioned production method may be discharged from a discharge unit 60, laminated, and the laminate 80 may be hardened to obtain a hardened product.

[0059] Each of the above manufacturing methods may be performed using a 3D printer having a configuration different from that of the 3D printer shown in FIG. 1. In this case, too, since the second slurry containing the above-mentioned hardening agent is used, a two-component mixed hydraulic composition (mixed slurry) having a sufficiently high mixing uniformity and excellent strength development can be obtained. A laminate formed using this two-component mixed hydraulic composition (mixed slurry) is prevented from sagging and also has excellent strength development. Therefore, the two-component mixed hydraulic composition (mixed slurry) can form a hardened product that is easy to apply and has excellent aesthetics.

[0060] To produce a two-component hydraulic composition (mixed slurry), a two-component hydraulic composition preparation kit for a 3D printer may be used, which includes the above-mentioned main material or a first slurry containing the main material, and the above-mentioned hardening material or a second slurry containing the main material, in separate states. The above-mentioned main material or a first slurry containing the main material, and the above-mentioned hardening material or a second slurry containing the main material may be contained in separate containers. Such a two-component hydraulic composition preparation kit can be stably stored for a long period of time because the two components are separate and not mixed. Furthermore, a two-component hydraulic composition with excellent strength development can be smoothly prepared at the construction site by mixing the first slurry and the second slurry using a 3D printer, for example, as shown in FIG. 1. Alternatively, the main material and the hardening material may be mixed with water at the construction site to prepare the first and second slurries, and then the two slurries may be mixed to prepare the two-component hydraulic composition.

[0061] The two-component hydraulic composition thus obtained contains the components of the main material and the components of the hardening material. The ratio of the hardening material to the main material in the two-component hydraulic composition may be 15 to 40 mass %, or 20 to 35 mass %. The total content of silica fume and metakaolin contained in the two-component hydraulic composition relative to 100 mass parts of the total amount of binders contained in the main material may be 8 to 40 mass parts, 15 to 40 mass parts, or 20 to 30 mass parts, from the viewpoint of obtaining a two-component hydraulic composition that is sufficiently easy to apply.

[0062] The content of alum relative to 100 parts by mass of the total amount of binders contained in the main material may be 6 parts by mass or less, 4 parts by mass or less, or 3 parts by mass or less. Such a two-component hydraulic composition has sufficiently excellent mixability, and therefore has a sufficiently uniform composition even when mixed using a static mixer. As a result, a set product with sufficiently high compressive strength can be obtained. Furthermore, sagging of the laminate can be sufficiently suppressed, and a set product with excellent appearance can be obtained. The content of alum relative to 100 parts by mass of the total amount of binders contained in the main material may be 1 part by mass or more, 1.5 parts by mass or more, or 2 parts by mass or more. This makes it possible to form a set product with sufficiently high compressive strength. An example of the content of alum relative to 100 parts by mass of the total amount of binders contained in the main material is 1 to 6 parts by mass.

[0063] The content of the alkali metal salt per 100 parts by mass of the total amount of binder contained in the main material may be 0.2 parts by mass or more, 0.5 parts by mass or more, or 1 part by mass or more, from the viewpoint of stably obtaining a cured product having sufficiently high compressive strength. The content of the alkali metal salt per 100 parts by mass of the total amount of binder contained in the main material may be 6 parts by mass or less, 4 parts by mass or less, or 3 parts by mass or less, from the viewpoint of suppressing an increase in the discharge pressure of the liquid feed pump. An example of the content of the alkali metal salt per 100 parts by mass of the total amount of binder contained in the main material is 0.2 to 6 parts by mass.

[0064] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments. For example, the mixing unit 40 in the 3D printer is not limited to a static mixer and may be a dynamic mixer. Furthermore, multiple mixers of the same type may be used, or two or more types of mixers may be used in combination.

[0065] The present disclosure includes the following contents. [1] A hardener used in a two-component hydraulic composition for a 3D printer, A hardening agent comprising alum, basic aluminum salts, silica fume, and alkali metal sulfates. [2] The hardening material according to [1], further comprising metakaolin. [3] The curing material according to [1] or [2], wherein the content of the alum relative to the total solid content of the curing material is 1 to 12 mass %. [4] The curing material according to any one of [1] to [3], wherein the average particle size of the alum is 0.01 to 1.0 mm. [5] The curing material according to any one of [1] to [4], wherein the content of the alkali metal sulfate relative to the total solid content of the curing material is 0.5 to 10 mass %. [6] A two-component hydraulic composition preparation kit for a 3D printer, comprising a main material or a first slurry containing the main material and a hardening material or a second slurry containing the main material, in a separated state, the base material includes cement, silica fume, and a retarder; The hardening material is the hardening material according to any one of [1] to [5]. A kit for preparing a two-component hydraulic composition for a 3D printer. [7] The kit for preparing a two-component hydraulic composition according to [6], wherein the ratio of the hardening material to the main material is 15 to 40% by mass. [8] A first slurry containing a base material including cement, silica fume, and a retarder, and water; A two-component hydraulic composition for 3D printers, obtained by mixing the hardening material according to any one of [1] to [5] with a second slurry containing water. [9] The two-component hydraulic composition according to [8], wherein the content of the alum is 1 to 6 parts by mass per 100 parts by mass of the total amount of binders contained in the main material.

[10] A hardened product obtained by hardening the two-component hydraulic composition described in [8] or [9] above.

[11] A first slurry containing a base material including cement, silica fume, and a retarder, and water; A method for producing a two-component hydraulic composition for a 3D printer, comprising a step of mixing a second slurry containing the hardening material according to any one of [1] to [5] and water.

[12] The method for producing a two-component hydraulic composition according to

[11] , wherein the first slurry and the second slurry are mixed using a static mixer.

[13] A method for producing a hardened product, comprising the steps of discharging the two-component hydraulic composition obtained by the method according to

[11] or

[12] above from a discharge part of a 3D printer, laminating the composition, and curing the laminate to obtain a hardened product. [Example]

[0066] The present disclosure will be described in detail below with reference to examples and comparative examples, although the present disclosure is not limited to the following examples.

[0067] (Examples 1 to 3, Comparative Examples 1 and 2) The following raw materials were prepared: <Material> Binder (C): High-early-strength Portland cement (manufactured by UBE Mitsubishi Cement Corporation) Binder (BFS): Ground granulated blast furnace slag (ground granulated blast furnace slag 4000, specific surface area 4670 cm 2 / g) Binder (SF): Silica fume (EFACO (trade name), manufactured by Tomoe Engineering Co., Ltd., BET specific surface area: 16.9 m 2 / g) Fine aggregate (S): Fine aggregate (Kashima silica sand No. 6 (product name), manufactured by Takano Shoji Co., Ltd., average particle size: 0.21 mm) Water reducing agent: Polyether-polycarboxylic acid-based high-performance water reducing agent (MELFLUX 6681F (product name), manufactured by BASF Japan Ltd.) Retardant: Sodium gluconate (reagent) Thickener: Water-soluble methylcellulose thickener (Marporose 90MP-300T (product name), manufactured by Matsumoto Oil & Fat Co., Ltd.) Antifoaming agent: Adekanate B115F (product name), manufactured by ADEKA Corporation Accelerator: Crystalline powder potassium alum (trade name), manufactured by Taimei Chemical Industry Co., Ltd. (average particle size: 60 μm) Metakaolin (MK): DG80V (product name), manufactured by Tomoe Engineering Co., Ltd. (average particle size: 1.0±0.1 μm, Al2O3 content: 45±2% by mass) Sodium sulfate: Reagent Water: Tap water Gelling agent: basic aluminum lactate (Taxeram M-160P (trade name), manufactured by Taki Chemical Co., Ltd.)

[0068] <Preparation of first slurry and second slurry> The raw materials in Table 1, except for water, were dry mixed to prepare a main material (premix powder). The values ​​in Table 1 indicate parts by mass based on 100 parts by mass of the binder contained in the main material. Water was added to this as shown in Table 1, and the mixture was kneaded at low speed in a Hobart mixer for 90 seconds. After the mixing was stopped for 30 seconds, any powder or paste adhering to the sides and bottom of the container was scraped off. After the pause, the mixture was kneaded at medium speed for 120 seconds to prepare a first slurry containing the main material. This first slurry was used in all Examples and Comparative Examples.

[0069] The raw materials shown in Table 2 were dry mixed in the mass ratios shown in Table 2 to prepare a hardening material (premix powder). Table 3 shows the blending amounts (parts by mass) of each raw material in Table 2, based on 100 parts by mass of the binder in the main material shown in Table 1. Water was added to this as shown in Table 3, and the mixture was mixed at low speed in a Hobart mixer for 90 seconds. After the mixing was stopped for 30 seconds, the powder and paste adhering to the sides and bottom of the container were scraped off. After the pause, the mixture was mixed at high speed for 120 seconds to prepare a second slurry for each example and comparative example having the composition shown in Table 3.

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3]

[0073] <Preparation of mixed slurry and formation of laminate> An installation system as shown in Figure 1 was prepared. A commercially available non-pulsating metering pump (Mono Pump (product name), manufactured by Heishin Soubi Co., Ltd.) was used as the first liquid feed pump 14 and the second liquid feed pump 24. Two commercially available static mixers (manufactured by Chihiro Co., Ltd., model: TA6-SUS20-3 (20A)) having the structure shown in Figure 2 were connected in series and used as the mixing section 40.

[0074] The first slurry having the composition shown in Table 1 was stored in the first storage unit 12 in Fig. 1, and the second slurry having the composition shown in Table 3 was stored in the second storage unit 22. The first liquid supply pump 14 and the second liquid supply pump 24 were then started, and the mixed slurry (two-component mixed hydraulic composition) was discharged from the discharge unit 60 (nozzle) attached downstream of the mixing unit to form the laminate 80. The mixing ratio of the second slurry to the first slurry was 1 / 3 on a volume basis (25 mass % on a mass basis). The discharge rate from the discharge unit 60 was constant at 2.3 L / min, and the movement speed of the discharge unit 60 was 120 mm / sec.

[0075] <Evaluation of sagging suppression> A laminate with 10 layers was formed using the hardener slurries of each Example and Comparative Example. Visual inspection of the side surfaces of the prepared laminate revealed that sagging on the side surfaces was more sufficiently suppressed in the Examples than in the Comparative Examples. The width W1 of the top layer (first layer) and the width W2 of the second layer (second layer) from the top of the laminates formed using the mixed slurries containing the hardeners of Comparative Example 1, Examples 1, and 3 were measured, and the spreading ratio was calculated using the following formula. The results are shown in Table 4. Spread rate (%) = (W2-W1) / W1 x 100

[0076] [Table 4]

[0077] As shown in Table 4, the two-component hydraulic compositions of Examples 1 and 3, which used a hardener containing sodium sulfate, had a smaller spreading rate than the two-component hydraulic composition of Comparative Example 1. From these results, it was confirmed that Examples 1 and 3 were easier to apply and had better strength development than Comparative Example 1, and that they could form hardened products with excellent aesthetics.

[0078] <Measurement of discharge pressure at the pump outlet> After the discharge of the mixed slurry from the discharge section 60 began, the pressure (discharge pressure) at the outlet of the first liquid feed pump was measured. The change in discharge pressure over time (measured every minute) when the mixed slurries containing the hardener of Comparative Example 1 and Examples 1, 2, and 3 were discharged, and the average value of the discharge pressure during the discharge pressure measurement period are shown in Table 5. In all Examples and Comparative Examples, the outlet of the first liquid feed pump showed a higher pressure than the outlet of the second liquid feed pump. Since the composition of the main material (first slurry) was the same in all Examples and Comparative Examples, it was confirmed that the pressure at the outlet of the first liquid feed pump was affected by the composition of the hardener discharged from the second liquid feed pump.

[0079] [Table 5]

[0080] As shown in Table 5, the discharge pressure of all Examples and Comparative Examples was within the allowable range. It was confirmed that the discharge pressure tended to increase as the content of sodium sulfate increased. This indicates that the discharge pressure can be reduced by adjusting the content of sodium sulfate in the hardener to a lower level.

[0081] <Evaluation of strength development> Using a construction system such as that shown in Figure 1, the mixed slurries prepared in each Example and Comparative Example were poured into a formwork so as to form a two-layer structure in the vertical direction. The surface was smoothed and the formwork was filled to create cylindrical specimens measuring φ50 mm x 100 mm. In accordance with JIS A 1108:2018 "Testing Method for Compressive Strength of Concrete," compressive strength tests were conducted on each specimen at ages of 7 and 28 days. After 6 days, the specimens were removed from the formwork and then cured in air at 20°C and 50% RH. The results are shown in Table 6.

[0082] [Table 6]

[0083] In the column for sodium sulfate content in Table 6, the "Binder Standard" column indicates the sodium sulfate content per 100 parts by mass of binder contained in the main material, and the "Hardening Agent Standard" column indicates the sodium sulfate content per total solid content of the hardener. Among the results in Table 6, the results for Comparative Example 1 and Examples 1 to 3, which had the same mixing ratio of raw materials other than sodium sulfate, are shown in Figure 3. The black plot in Figure 3 indicates the compressive strength at 7 days, and the white plot indicates the compressive strength at 28 days. As shown in Table 6 and Figure 3, it was confirmed that the compressive strength of the hardened product increased as the sodium sulfate content in the hardener increased. Furthermore, as shown in Table 6, the compressive strength of the hardened product decreased in Comparative Example 2, which added a larger amount of potassium alum than in Comparative Example 1. This is thought to be due to the fact that hardening progressed rapidly in some areas during mixing of the first and second slurries, resulting in insufficient mixing and an insufficient uniform composition of the mixed slurry.

[0084] <Evaluation of Mixability> The cross sections of the hardened body of Comparative Example 1 (7 days old) and the hardened body of Example 1 (7 days old), both prepared in the same manner as in the evaluation of strength development, were photographed with a digital camera. Observation of the photographs revealed that the hardened body of Comparative Example 1 had more white and black clumps in the cross section, while the hardened body of Example 1 had a more uniform structure. The photographs were binarized using Image J to calculate the area ratio of the white areas to the entire image. The result was 18% for Comparative Example 1 and 11% for Example 1. This value also confirmed that the hardened body of Example 1 had a more uniform structure. This is thought to be due to the fact that a more uniform mixed slurry was prepared in Example 1 than in Comparative Example 1. [Explanation of symbols]

[0085] 10...first supply section, 12...first storage section, 14...first liquid delivery pump, 20...second supply section, 22...second storage section, 24...second liquid delivery pump, 30...junction section, 32...flow path, 40...mixing section (static mixer), 41...element, 45...cylinder, 60...discharge section, 70...position adjustment section, 80...laminated body.

Claims

1. A hardening material used in a two-component hydraulic composition for a 3D printer, A hardening agent comprising alum, basic aluminum salts, silica fume, and alkali metal sulfates.

2. The hardening material of claim 1 further comprising metakaolin.

3. The hardener according to claim 1 or 2, wherein the content of the alum relative to the total solid content of the hardener is 1 to 12 mass%.

4. The hardener according to claim 1 or 2, wherein the average particle size of the alum is 0.01 to 1.0 mm.

5. The hardener according to claim 1 or 2, wherein the content of the alkali metal sulfate relative to the total solid content of the hardener is 0.5 to 10 mass%.

6. A two-component hydraulic composition preparation kit for a 3D printer, comprising a main material or a first slurry containing the main material, and a hardening material or a second slurry containing the hardening material, in a separated state, the base material includes cement, silica fume, and a retarder; A kit for preparing a two-component hydraulic composition for a 3D printer, wherein the hardener is the hardener according to claim 1 or 2.

7. 7. The kit for preparing a two-component hydraulic composition according to claim 6, wherein the ratio of the hardening material to the main material is 15 to 40% by mass.

8. a first slurry containing a base material including cement, silica fume, and a retarder, and water; A two-component hydraulic composition for 3D printers, obtained by mixing the hardening material according to claim 1 or 2 with a second slurry containing water.

9. 9. The two-component hydraulic composition according to claim 8, wherein the content of said alum is 1 to 6 parts by mass per 100 parts by mass of the total amount of binders contained in said main material.

10. A hardened product obtained by hardening the two-component hydraulic composition according to claim 8.

11. a first slurry containing a base material including cement, silica fume, and a retarder, and water; A method for producing a two-component hydraulic composition for a 3D printer, comprising a step of mixing the hardening material according to claim 1 or 2 with a second slurry containing water.

12. The method for producing a two-component hydraulic composition according to claim 11, wherein the first slurry and the second slurry are mixed using a static mixer.

13. A method for producing a cured product, comprising the steps of discharging the two-component hydraulic composition obtained by the production method according to claim 11 from a discharge part of a 3D printer to form a laminate, and curing the laminate to obtain a cured product.

Images