Coal gangue-based temperature control and humidity control material for 3D printing and preparation method of coal gangue-based temperature control and humidity control material

Abstract

The invention relates to a coal gangue-based temperature control and humidity control material for 3D printing and a preparation method thereof, two wastes of coal gangue and camellia oleifera shells are taken as main raw materials, the purpose of treating wastes with wastes is realized, the concept of circular economy is met, and the cost is low. Rapid hardening is achieved through calcium formate, rheology controllability is achieved through a rheology modifier, and the core problems of the 3D printing material in the aspects of printability and early strength are successfully solved. The functions of temperature control (phase change microcapsules) and humidity regulation (air entraining-fiber porous system) are integrated in a printing material, so that a printed building component becomes an intelligent environment regulator. Due to the addition of the camellia oleifera shell fibers, humidifying is assisted, the reinforcing and toughening effects are achieved, and the integrity and long-term durability of a printed component are improved.

Description

Technical Field

[0001] This invention relates to the intersection of green building materials and additive manufacturing technology, specifically to a coal gangue-based temperature and humidity control material for 3D printing and its preparation method. Background Technology

[0002] With the innovation of the construction industry, 3D printing technology (also known as additive manufacturing) has shown great potential in the construction field. Its advantages lie in its ability to achieve moldless rapid prototyping, high design freedom, saving manpower and materials, and the ability to construct complex geometric structures that are difficult to achieve with traditional processes. However, the success of 3D printing in construction is highly dependent on the performance of the printing material itself. It requires the material to not only have pumpable and extrudable rheological properties, but also to rapidly build up strength after extrusion to support subsequent layer-by-layer printing, that is, to have good "constructability".

[0003] At the same time, people's demands for the comfort and energy efficiency of built environments are increasing. Smart materials with temperature control (absorbing or releasing heat through phase change materials to stabilize room temperature) and humidity regulation (adsorbing or releasing water vapor through porous materials to regulate humidity) functions have become a research hotspot. These materials can passively regulate the indoor microclimate, reduce building energy consumption, and improve living comfort.

[0004] However, combining 3D printing technology with temperature and humidity control materials faces significant technical bottlenecks: (1) The contradiction between rheological properties and functions: The composition of traditional temperature and humidity control materials (such as porous cement-based materials and composite materials containing a large amount of phase change materials) often has an adverse effect on the rheological properties of the printing slurry. For example, the addition of phase change materials may introduce lubrication or air entrainment effect, which will destroy the stability of the slurry; while the air entraining agent or lightweight aggregate added to build the porous structure required for humidity control function will significantly reduce the yield stress and viscosity of the slurry, leading to deformation or collapse of the printed component.

[0005] (2) Matching strength development with printing speed: 3D printing requires materials to have a fast initial setting rate and sufficient early strength. However, many geopolymers or solid waste-based cementitious materials have slow hydration / reaction rates, making it difficult to meet the requirements of rapid construction. Conventional accelerators can accelerate setting, but may impair the later properties of the material or affect its functionality.

[0006] (3) Solid waste utilization and performance balance: Using industrial solid waste such as coal gangue as the main raw material is in line with the concept of sustainable development. However, the activity of coal gangue fluctuates greatly, the rheological properties of the prepared slurry are difficult to control, and the mechanical properties and functionality (such as pore structure) of its products are not easy to precisely control.

[0007] Therefore, there is an urgent need to develop a new type of material that can solve the above problems in a synergistic way. It can not only meet the strict process requirements of 3D printing, but also give the printed parts excellent temperature and humidity control functions, realize the high-value-added resource utilization of solid waste, and reduce the cost of materials. Summary of the Invention

[0008] Based on this, the purpose of this invention is to overcome the shortcomings of the prior art and provide a coal gangue-based temperature and humidity control material for 3D printing and its preparation method. This material achieves a unity of functionality, printability and environmental friendliness.

[0009] First aspect: A coal gangue-based temperature and humidity control material for 3D printing, comprising the following components by mass parts: Coal gangue active powder: 100 parts; Calcium hydroxide: 10-15 parts; Calcium formate: 3-5 parts; Camellia oleifera fruit shell fiber: 5-10 parts; Phase change microcapsules: 10-20 parts; Air-entraining agent: 0.1-0.5 parts; Rheology modifier: 0.1-1 part; Water: 40-50 parts; The active coal gangue powder is composed of 70 parts coal gangue, 15 parts limestone and 15 parts iron tailings.

[0010] The functions of each component in the coal gangue-based temperature and humidity control material for 3D printing of this invention are as follows: Coal gangue active powder, as the main cementing component, exhibits high pozzolanic activity after appropriate thermal activation treatment. It hardens upon contact with water and can react with calcium hydroxide to form a strong framework. Simultaneously, it possesses good fluidity and plasticity, making it suitable for 3D printing and forming the basis for the application of temperature and humidity control materials. Calcium hydroxide, as an activator, not only activates the activity of coal gangue but also reacts with carbon dioxide in the air to generate calcium carbonate, enhancing later-stage strength. Calcium formate, as an early-strength agent, significantly accelerates the hydration and hardening process of the coal gangue-calcium hydroxide system, meeting the rapid hardening requirements of 3D printing. Camellia oleifera fruit shell fiber, after treatment, serves as a reinforcing fiber, improving the material's crack resistance and toughness, preventing cracking during printing. The plant fiber structure also possesses lightweight, porous, and thermal insulation properties. Phase change microcapsule materials absorb or release heat through a phase change process, regulating ambient temperature fluctuations and improving building energy efficiency. An air-entraining agent introduces uniform microbubbles into the material, forming a porous structure that provides space for moisture adsorption, achieving the humidity control function. Rheology modifiers precisely control the viscosity and yield stress of the slurry, ensuring that the material is both easy to extrude and has good buildability.

[0011] The innovations of this invention are mainly reflected in the following four aspects: (1) Solid waste synergistic activation and rapid hardening system: Calcined coal gangue active powder is used as the main cementing component, and calcium hydroxide is used as an alkaline activator. The two undergo a geopolymer reaction to generate cementitious products. Calcium formate is innovatively introduced as a composite coagulant, which can not only significantly accelerate the formation of early hydration products such as ettringite, providing rapid early strength growth to meet the needs of layer-by-layer printing, but also has a much smaller negative impact on later strength than traditional calcium chloride or aluminate coagulants. Due to the fineness of the coal gangue active powder, the slurry after being combined with calcium hydroxide has good fluidity and plasticity, which is very beneficial for construction.

[0012] (2) Hierarchical pore structure and humidity regulation mechanism: By introducing an air-entraining agent, a large number of uniform and closed microbubbles are introduced into the slurry. At the same time, the camellia fruit shell fiber itself has abundant natural pores. The two work together to construct a hierarchical pore structure from the nanometer to the micrometer scale. This structure provides a huge specific surface area and channels for the adsorption and desorption of water vapor, thus endowing the material with excellent humidity regulation capabilities.

[0013] (3) Temperature regulation and enhancement mechanism: By incorporating phase change microcapsules, when the ambient temperature fluctuates, the phase change material inside the microcapsules undergoes a solid-liquid reversible transition. During this process, it absorbs or releases a large amount of latent heat, thereby buffering temperature changes and achieving intelligent regulation of indoor temperature. At the same time, the camellia fruit shell fiber dispersed in the matrix acts as a micro-reinforcing material, effectively inhibiting crack propagation caused by plastic shrinkage and drying shrinkage during the printing process, and enhancing the toughness and crack resistance of the material.

[0014] (4) Precise rheological control strategy: In view of the characteristics of coal gangue-based slurry and the rheological challenges that air-entraining agents and phase change microcapsules may bring, a rheology modifier was specially introduced. It can significantly improve the yield stress and viscosity of the slurry through physical entanglement and hydration film effect, ensuring that the slurry maintains shape stability before extrusion (good buildability), can pass smoothly through the nozzle during extrusion (good extrudability), and quickly recovers structural strength after extrusion.

[0015] In summary, compared with existing technologies, the advantages of this invention are as follows: It uses coal gangue and camellia fruit shells as the main raw materials, achieving "waste-to-waste treatment," which aligns with the concept of a circular economy and is cost-effective. Rapid hardening is achieved through calcium formate, and rheological control is achieved through rheology modifiers, successfully solving the core challenges of printability and early strength in 3D printing materials. The integration of temperature control (phase change microcapsules) and humidity regulation (air-entrained fiber porous system) functions into the printing material makes the printed building component itself an intelligent environmental regulator. The addition of camellia fruit shell fibers not only assists in humidity regulation but also enhances toughness, improving the integrity and long-term durability of the printed component.

[0016] As a preferred embodiment, the SiO2 content in the coal gangue is not less than 60% by mass, the calcium oxide content in the limestone is not less than 40%, and the SiO2 content in the iron tailings is not less than 70%.

[0017] As a preferred embodiment, the preparation method of the coal gangue active powder includes the following steps: crushing, mixing, and grinding the coal gangue, limestone, and iron tailings, then calcining them at 700-900℃ for 5-10 hours, and grinding them to a specific surface area of ​​not less than 400 m² after the reaction. 2 / kg, to obtain the active coal gangue powder; the pozzolanic activity index of the active coal gangue powder is not less than 0.85.

[0018] Natural coal gangue is mainly composed of kaolinite and quartz crystals, with a very stable structure. After high-temperature calcination, the crystal structure is destroyed, and components such as SiO2 and aluminum oxide recombine with calcium oxide and SiO2 from limestone and iron tailings to form new phases. These phases have pozzolanic activity; if the pozzolanic activity is too low, the strength of the formed material will be low. Furthermore, since coal gangue contains a certain amount of coal, its calcination process requires no additional energy consumption. More preferably, the calorific value of the coal gangue is below 1000 kcal / kg. Coal gangue with a higher calorific value can be used for power generation and has higher utilization value; while coal gangue with a calorific value below 1000 kcal / kg has limited utilization pathways and is often regarded as solid waste, making its resource utilization more urgent. If the specific surface area of ​​the coal gangue active powder is too low, the particles will be too coarse, resulting in poor reactivity.

[0019] As a preferred embodiment, the preparation method of the camellia oleifera fruit shell fiber includes the following steps: crushing the camellia oleifera fruit shell, treating it in a 1-5% sodium hydroxide solution at 80-100℃ for 1-3 hours, washing it until pH=7-8, drying it, and then mechanically grinding it for 0.5-2 hours to obtain the camellia oleifera fruit shell fiber with a length of 0.1-2 mm. After modification with an alkaline solution and shortening the fiber to 0.1-2 mm, the strength and toughness of the camellia oleifera fruit shell fiber can be improved, and its compatibility with the matrix is ​​good.

[0020] As a preferred embodiment, the preparation method of the phase change microcapsules includes the following steps: reacting a 37% (w / w) formaldehyde solution and an 80% urea solution at 55-90℃ for 2.5-3.5 h to obtain a urea-formaldehyde resin prepolymer solution; reacting the urea-formaldehyde resin prepolymer solution with a 50% (w / w) n-octadecane solution at pH 4-5 and a temperature of 60-80℃ for 1-2 h; then washing and drying the resulting reaction product to obtain white powdered n-octadecane-urea-formaldehyde resin phase change microcapsules, wherein the average particle size of the phase change microcapsules is 5-20 μm and the phase change temperature is 20-28℃. If the particle size of the phase change microcapsules is too large, it will affect stirring; if the particle size is too small, the temperature control effect will be poor. A phase change temperature controlled at 20-28℃ is a suitable living environment.

[0021] As a preferred embodiment, the method for preparing the n-octadecane solution includes the following steps: mixing Tween 80, Span 80 and n-octadecane in water at a mass ratio of 1:1:30~50, wherein the mass concentration of n-octadecane in the aqueous solution is 50%, and stirring at a speed of 500~1000 rpm for 10~20 min to obtain the n-octadecane solution.

[0022] As a preferred embodiment, the air-entraining agent is at least one of rosin thermal polymers, alkylbenzene sulfonates, or protein-based air-entraining agents.

[0023] As a preferred embodiment, the rheology modifier is hydroxypropyl methylcellulose and / or a polycarboxylate superplasticizer. By changing the amount of free water, the fluidity, viscosity, and yield stress of the slurry are adjusted, thereby ensuring the printability of the slurry.

[0024] As a preferred embodiment, the slump is 150-180 mm, the initial setting time is no more than 40 min, and the final setting time is no more than 6 h; the yield stress is 200.00-600.00 Pa, and the apparent viscosity is 0.50-1.50 Pa·s; the hardened compressive strength is no less than 15 MPa, the thermal conductivity is no higher than 0.35 W / (m·K), and the 24-hour moisture absorption is no less than 50 g / m³. 2 Suitable yield stress and apparent viscosity ensure good extrudability and constructability.

[0025] The second aspect: A method for preparing a coal gangue-based temperature and humidity control material for 3D printing as described in the first aspect includes the following steps: Dry mixing: 100 parts of the coal gangue active powder, 10-15 parts of calcium hydroxide, 3-5 parts of calcium formate, 5-10 parts of camellia fruit shell fiber, 10-20 parts of phase change microcapsules and 0.1-1 parts of rheology modifier are stirred and mixed at a speed of 10-50 rpm for 5-15 minutes until the mixture is uniform to obtain a dry mixture. Wet mixing: Add 40-50 parts of water and 0.1-0.5 parts of air-entraining agent to the dry mixture, stir at 10-50 rpm for 1-3 minutes, and then stir at 100-150 rpm for 2-5 minutes to obtain the coal gangue-based temperature and humidity control material for 3D printing. Detailed Implementation

[0026] A coal gangue-based temperature and humidity control material for 3D printing, comprising the following components by mass parts: Coal gangue active powder: 100 parts; Calcium hydroxide: 10-15 parts; Calcium formate: 3-5 parts; Camellia oleifera fruit shell fiber: 5-10 parts; Phase change microcapsules: 10-20 parts; Air-entraining agent: 0.1-0.5 parts; Rheology modifier: 0.1-1 part; Water: 40-50 parts; The active coal gangue powder consists of 70 parts coal gangue, 15 parts limestone, and 15 parts iron tailings. The SiO2 content in the coal gangue is not less than 60%, the calcium oxide content in the limestone is not less than 40%, and the SiO2 content in the iron tailings is not less than 70%. The pozzolanic activity of the active coal gangue powder is not less than 0.85.

[0027] The air-entraining agent is at least one of rosin thermal polymers, alkylbenzene sulfonates, or protein-based air-entraining agents. These substances are surfactants. Common alkylbenzene sulfonate air-entraining agents include sodium dodecyl sulfonate (analytical grade). Rosin thermal polymers or protein-based air-entraining agents are obtained by reacting plant or animal proteins with alkaline solutions. In this embodiment of the invention, these two substances were purchased from Chongqing Lingqi Building Materials Co., Ltd.

[0028] The rheology modifiers hydroxypropyl methylcellulose and / or polycarboxylate superplasticizers were used. In this embodiment of the invention, the polycarboxylate superplasticizer was purchased from Guangdong Hongqiang New Materials Co., Ltd., and the hydroxypropyl methylcellulose rheology modifier was of analytical grade.

[0029] Calcium hydroxide, calcium formate, and alkylbenzene sulfonate air-entraining agents are all analytical chemical reagents.

[0030] A method for preparing a coal gangue-based temperature and humidity control material for 3D printing includes the following steps: Preprocessing: The preparation method of active coal gangue powder is as follows: coal gangue, limestone and iron tailings are crushed, mixed and ground in a mass ratio of 75:10:15 until the specific surface area is ≥300 m². 2After processing, the powder is calcined at 700-900℃ for 5-10 hours. After the reaction is complete, it is ground to a specific surface area of ​​not less than 400 m². 2 / kg, to obtain active coal gangue powder.

[0031] The preparation method of camellia fruit shell fiber is as follows: After crushing the camellia fruit shell, it is treated in a 1-5% sodium hydroxide solution at 80-100℃ for 1-3 hours, washed until pH=7-8, dried, and then mechanically ground for 0.5-2 hours to obtain camellia fruit shell fibers with a length of 0.1-2 mm.

[0032] The preparation method of phase change microcapsules is as follows: a 37% formaldehyde solution and an 80% urea solution are reacted at 55-90℃ for 2.5-3.5h to obtain a urea-formaldehyde resin prepolymer solution; the urea-formaldehyde resin prepolymer solution is reacted with a 50% n-octadecane solution at pH=4-5 and temperature of 60-80℃ for 1-2h; the resulting reaction product is then washed and dried to obtain white powdered n-octadecane-urea-formaldehyde resin phase change microcapsules. The phase change microcapsules have an average particle size of 5-20μm and a phase change temperature of 20-28℃.

[0033] In this embodiment of the invention, the method for preparing the n-octadecane solution is as follows: Tween 80, Span 80 and n-octadecane are mixed in water at a mass ratio of 1:1:30~50, the mass concentration of n-octadecane in the aqueous solution is 50%, and the mixture is stirred at a speed of 500~1000 rpm for 10~20 min to obtain the n-octadecane solution.

[0034] Dry Mixing: Mix 100 parts of coal gangue active powder, 10-15 parts of calcium hydroxide, 3-5 parts of calcium formate, 5-10 parts of camellia fruit shell fiber, 10-20 parts of phase change microcapsules and 0.1-1 parts of rheology modifier at a speed of 10-50 rpm for 5-15 minutes until the mixture is uniform to obtain a dry mix. Wet mixing: Add 40-50 parts water and 0.1-0.5 parts air-entraining agent to the dry mixture, stir at 10-50 rpm for 1-3 minutes, and then stir at 100-150 rpm for 2-5 minutes to obtain coal gangue-based temperature and humidity control material for 3D printing.

[0035] The prepared coal gangue-based temperature and humidity controlled material for 3D printing has a slump of 150-180 mm, an initial setting time of no more than 40 min, and a final setting time of no more than 6 h. Its yield stress is 200.00-600.00 Pa, and its apparent viscosity is 0.50-1.50 Pa·s. After hardening, its compressive strength is no less than 15 MPa, its thermal conductivity is no higher than 0.35 W / (m·K), and its 24-hour moisture absorption is no less than 50 g / m³. 2.

[0036] Example 1 A coal gangue-based temperature and humidity control material for 3D printing comprises the following components by mass: 100 parts of active coal gangue powder; 10 parts of calcium hydroxide; 3 parts of calcium formate; 5 parts of camellia oleifera fruit shell fiber; 12 parts of phase change microcapsules; 0.1 parts of air-entraining agent; 0.5 parts of hydroxypropyl methylcellulose; and 45 parts of water.

[0037] Its preparation method includes the following steps: 1) Coal gangue active powder: Coal gangue, limestone, and iron tailings are ground in a mass ratio of 75:10:15 until the specific surface area is ≥300 m². 2 After being calcined at 800℃ for 6 hours, the powder was cooled and then ground to a specific surface area of ​​450 m². 2 / kg, and its pozzolanic activity index was 0.88 according to GB / T1596-2017.

[0038] 2) Camellia oleifera fruit shell fiber: Crush the camellia oleifera fruit shell, place it in a 3% NaOH solution, treat it at 90℃ for 2 hours, filter, wash with water until neutral, dry and grind it to an average length of 0.5 mm.

[0039] 3) Phase change microcapsules: A urea-formaldehyde resin prepolymer solution was obtained by reacting a 37% (w / w) formaldehyde solution and an 80% (w / w) urea solution at 90℃ for 170 min (addition and condensation reactions). The urea-formaldehyde resin prepolymer solution was then reacted with a 50% (w / w) n-octadecane solution at pH 4.5 and 80℃ for 2 h. The resulting reaction product was washed and dried to obtain white powdery n-octadecane-urea-formaldehyde resin phase change microcapsules with an average particle size of 8.6 μm and a phase change temperature of 25℃.

[0040] 4) Pour the coal gangue active powder, calcium hydroxide, calcium formate, camellia fruit shell fiber, phase change microcapsules and HPMC into a planetary mixer and dry mix at 60 rpm for 10 minutes to obtain a dry mix.

[0041] 5) Add water and air-entraining agent to the dry mixture, stir at 60 rpm for 2 minutes, and then stir at 120 rpm for 3 minutes to obtain coal gangue-based temperature and humidity control material for 3D printing.

[0042] Example 2 A coal gangue-based temperature and humidity control material for 3D printing comprises the following components by mass: 100 parts of active coal gangue powder; 15 parts of calcium hydroxide; 4 parts of calcium formate; 8 parts of camellia oleifera fruit shell fiber; 15 parts of phase change microcapsules; 0.2 parts of air-entraining agent; 0.1 parts of polycarboxylate superplasticizer; and 50 parts of water.

[0043] Its preparation method includes the following steps: 1) Coal gangue active powder: Coal gangue, limestone, and iron tailings are ground in a mass ratio of 75:10:15 until the specific surface area is ≥300 m². 2 After being calcined at 900℃ for 5 hours, the powder was cooled and then ground to a specific surface area of ​​450 m². 2 / kg, and its pozzolanic activity index was 0.87 according to GB / T1596-2017.

[0044] 2) Camellia oleifera fruit shell fiber: Crush the camellia oleifera fruit shell, place it in a 5% NaOH solution, treat it at 80℃ for 3 hours, filter, wash with water until neutral, dry and grind it to an average length of 0.2 mm.

[0045] 3) Phase change microcapsules: A urea-formaldehyde resin prepolymer solution was obtained by adding and condensing a 37% (w / w) formaldehyde solution and an 80% (w / w) urea solution at 80°C for 200 min. Then, the urea-formaldehyde resin prepolymer solution was reacted with a 50% (w / w) n-octadecane solution at pH 4.5 and 80°C for 2 h. The resulting reaction product was washed and dried to obtain white powdery n-octadecane-urea-formaldehyde resin phase change microcapsules with an average particle size of 10.3 μm and a phase change temperature of 23°C.

[0046] 4) Pour the coal gangue active powder, calcium hydroxide, calcium formate, camellia fruit shell fiber, phase change microcapsules and HPMC into a planetary mixer and dry mix at 60 rpm for 10 minutes to obtain a dry mix.

[0047] 5) Add water and air-entraining agent to the dry mixture, stir at 60 rpm for 2 minutes, and then stir at 120 rpm for 3 minutes to obtain coal gangue-based temperature and humidity control material for 3D printing.

[0048] Example 3 A coal gangue-based temperature and humidity control material for 3D printing comprises the following components by mass: 100 parts of active coal gangue powder; 10 parts of calcium hydroxide; 5 parts of calcium formate; 10 parts of camellia oleifera fruit shell fiber; 20 parts of phase change microcapsules; 0.5 parts of air-entraining agent; 1 part of hydroxypropyl methylcellulose; and 40 parts of water.

[0049] Its preparation method includes the following steps: 1) Coal gangue active powder: Coal gangue, limestone, and iron tailings are ground in a mass ratio of 75:10:15 until the specific surface area is ≥300 m². 2 After being calcined at 700℃ for 10 hours, the powder was cooled and then ground to a specific surface area of ​​450 m².2 / kg, and its pozzolanic activity index was 0.85 according to GB / T1596-2017.

[0050] 2) Camellia oleifera fruit shell fiber: Crush the camellia oleifera fruit shell, place it in a 4% NaOH solution, treat it at 100℃ for 2 hours, filter, wash with water until neutral, dry and grind it to an average length of 0.1 mm.

[0051] 3) Phase change microcapsules: A urea-formaldehyde resin prepolymer solution was obtained by adding and condensing a 37% (w / w) formaldehyde solution and an 80% (w / w) urea solution at 60°C for 210 min. Then, the urea-formaldehyde resin prepolymer solution was reacted with a 50% (w / w) n-octadecane solution at pH 4.5 and 80°C for 2 h. The resulting reaction product was washed and dried to obtain white powdery n-octadecane-urea-formaldehyde resin phase change microcapsules with an average particle size of 16.2 μm and a phase change temperature of 22°C.

[0052] 4) Pour the coal gangue active powder, calcium hydroxide, calcium formate, camellia fruit shell fiber, phase change microcapsules and HPMC into a planetary mixer and dry mix at 60 rpm for 10 minutes to obtain a dry mix.

[0053] 5) Add water and air-entraining agent to the dry mixture, stir at 60 rpm for 2 minutes, and then stir at 120 rpm for 3 minutes to obtain coal gangue-based temperature and humidity control material for 3D printing.

[0054] Performance testing The performance of the coal gangue-based temperature and humidity control materials for 3D printing prepared in Examples 1-3 was tested, and the results are shown in Table 1. Table 1. Properties of coal gangue-based temperature and humidity control materials for 3D printing prepared in Examples 1-3

[0055] As shown in Table 1, the coal gangue-based temperature and humidity control materials prepared in Examples 1-3 of this invention exhibit excellent fluidity and a short initial setting time, meeting the requirements of rapid setting for 3D printing. The materials possess high mechanical strength, satisfying application needs in wall materials, infill structures, and other scenarios. Their thermal conductivity is significantly lower than that of typical building walls and steel structures, demonstrating excellent thermal insulation performance, with moisture absorption exceeding 50 g / m³. 2It exhibits high humidity regulation capability. Furthermore, the yield stress during the material forming stage is 200.00-600.00 Pa, and the apparent viscosity is 0.50-1.50 Pa·s, ensuring good extrudability and buildability. The 3D printing process of the material of this invention is smooth, without clogging or flow interruption, and the printed body has good uprightness without collapse or deformation. The finished product has excellent temperature and humidity regulation capabilities.

[0056] The above embodiments are merely illustrative of several implementations of the present invention, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of the invention patent. For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A coal gangue-based temperature and humidity control material for 3D printing, characterized in that, Based on parts by mass, it includes the following components: Coal gangue active powder: 100 parts; Calcium hydroxide: 10-15 parts; Calcium formate: 3-5 parts; Camellia oleifera fruit shell fiber: 5-10 parts; Phase change microcapsules: 10-20 parts; Air-entraining agent: 0.1-0.5 parts; Rheology modifier: 0.1-1 part; Water: 40-50 parts; The active coal gangue powder is composed of 70 parts coal gangue, 15 parts limestone and 15 parts iron tailings.

2. The coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, By mass ratio, the SiO2 content in the coal gangue is not less than 60%, the calcium oxide content in the limestone is not less than 40%, and the SiO2 content in the iron tailings is not less than 70%.

3. The coal gangue-based temperature and humidity control material for 3D printing according to claim 2, characterized in that, The preparation method of the coal gangue active powder includes the following steps: crushing, mixing, and grinding the coal gangue, limestone, and iron tailings, then calcining them at 700-900℃ for 5-10 hours, and grinding them to a specific surface area of ​​not less than 400 m² after the reaction. 2 / kg, to obtain the active coal gangue powder; the pozzolanic activity index of the active coal gangue powder is not less than 0.

85.

4. The coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, The preparation method of the camellia fruit shell fiber includes the following steps: after crushing the camellia fruit shell, it is treated in a sodium hydroxide solution with a mass fraction of 1-5% at 80-100℃ for 1-3 hours, washed until pH=7-8, dried, and then mechanically ground for 0.5-2 hours to obtain the camellia fruit shell fiber with a length of 0.1-2 mm.

5. The coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, The preparation method of the phase change microcapsules includes the following steps: reacting a 37% formaldehyde solution and an 80% urea solution at 55-90℃ for 2.5-3.5h to obtain a urea-formaldehyde resin prepolymer solution; reacting the urea-formaldehyde resin prepolymer solution with a 50% n-octadecane solution at pH=4-5 and a temperature of 60-80℃ for 1-2h; then washing and drying the obtained reaction product to obtain a white powdery n-octadecane-urea-formaldehyde resin phase change microcapsules, wherein the phase change microcapsules have an average particle size of 5-20μm and a phase change temperature of 20-28℃.

6. The coal gangue-based temperature and humidity control material for 3D printing according to claim 5, characterized in that, The method for preparing the n-octadecane solution includes the following steps: mixing Tween 80, Span 80 and n-octadecane in water at a mass ratio of 1:1:30~50, wherein the mass concentration of n-octadecane in the aqueous solution is 50%, and stirring at a speed of 500~1000 rpm for 10~20 min to obtain the n-octadecane solution.

7. The coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, The air-entraining agent is at least one of rosin thermopolymers, alkylbenzene sulfonates, or protein-based air-entraining agents.

8. The method for preparing a coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, The rheology modifier is hydroxypropyl methylcellulose and / or polycarboxylate superplasticizer.

9. The coal gangue-based temperature and humidity control material for 3D printing according to claim 1, characterized in that, The slump is 150-180 mm, the initial setting time is no more than 40 min, and the final setting time is no more than 6 h; the yield stress is 200.00-600.00 Pa, and the apparent viscosity is 0.50-1.50 Pa·s; the compressive strength after hardening is no less than 15 MPa, the thermal conductivity is no more than 0.35 W / (m·K), and the 24-hour moisture absorption is no less than 50 g / m³. 2 .

10. A method for preparing the coal gangue-based temperature and humidity control material for 3D printing according to any one of claims 1 to 9, characterized in that, Includes the following steps: Dry mixing: 100 parts of the coal gangue active powder, 10-15 parts of calcium hydroxide, 3-5 parts of calcium formate, 5-10 parts of camellia fruit shell fiber, 10-20 parts of phase change microcapsules and 0.1-1 parts of rheology modifier are stirred and mixed at a speed of 10-50 rpm for 5-15 minutes until the mixture is uniform to obtain a dry mixture. Wet mixing: Add 40-50 parts of water and 0.1-0.5 parts of air-entraining agent to the dry mixture, stir at 10-50 rpm for 1-3 minutes, and then stir at 100-150 rpm for 2-5 minutes to obtain the coal gangue-based temperature and humidity control material for 3D printing.

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