High-performance low-thermal-conductivity heat pipe support and preparation process thereof

Abstract

This invention relates to the field of thermal pipe support technology, and discloses a high-performance, low-thermal-conductivity thermal pipe support and its preparation process. This thermal pipe support, through adjusting the base material ratio and adding functional additives and glass fiber water-absorbing agents, possesses excellent thermal insulation performance and high compressive strength. Magnesium oxide has excellent infrared radiation absorption and scattering capabilities, which can block radiative heat transfer paths at high temperatures, significantly reducing the thermal conductivity. Furthermore, uniform bubbles and magnesium oxide work synergistically to suppress gas thermal convection, thus optimizing thermal insulation performance. The three-dimensional reinforcing structure formed by alkali-free glass fiber within the matrix, combined with the optimization of interfacial bonding performance by fly ash, significantly improves compressive strength. Simultaneously, hyaluronic acid has excellent water absorption properties; it is squeezed out during shrinkage deformation, releasing moisture and effectively reducing plastic shrinkage, thereby improving the strength of foamed cement.

Description

Technical Field

[0001] This invention relates to the field of thermal pipe support technology, specifically to a high-performance, low-thermal-conductivity thermal pipe support and its manufacturing process. Background Technology

[0002] With the acceleration of urbanization and the increasing prominence of building energy consumption, the development of high-efficiency thermal insulation materials has become an important research direction in the field of building energy conservation. Currently, commonly used thermal insulation materials mainly include two categories: organic foam plastics and inorganic insulation materials. While organic foam plastics have advantages such as low density and good insulation performance, their poor flammability, easy aging, and poor dimensional stability pose difficulties for firefighting and rescue operations, and they are prone to producing toxic gases in high-temperature environments. Inorganic insulation materials, on the other hand, have advantages such as good fire resistance, low deformation coefficient, and strong aging resistance. However, when lightweight aggregates are added alone or air entrainment is used to reduce the material density, the strength of the insulation material is often neglected, resulting in a very short service life.

[0003] Foamed cement, as a new type of energy-saving and environmentally friendly building material, has shown broad prospects in the fields of building energy conservation and structural filling due to its comprehensive advantages such as lightweight, thermal insulation, sound insulation, fire resistance, and waterproofing. However, current foamed cement still has some problems, such as uneven air bubble distribution, increased density, and reduced strength. In addition, traditional foamed cement is prone to radiation under high temperature environments and creep deformation under long-term load, leading to a decrease in compressive strength and crack resistance. In the future, it is necessary to further improve its comprehensive performance and engineering applicability by optimizing the foaming process, improving the mix design, and developing reinforcement technologies.

[0004] The invention patent with application number CN202010030834.2 discloses a foamed cement reinforcing agent and foamed cement using the reinforcing agent. It uses nanofibers as the core of cement hardening, thereby improving the toughness and strength of cement after hardening. Silica fume plays the role of filling gaps, while the fiber depth participates in the cement hardening and gap filling on the surface of nanofibers, playing a preliminary bridging and subsequent strengthening role. However, this invention fails to solve the problem of uneven bubble distribution and easy creep deformation. Based on this, the present invention provides a foamed cement with uniform bubble distribution and reinforcement. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance, low-thermal-conductivity heat pipe support and its manufacturing process.

[0006] The objective of this invention can be achieved through the following technical solutions: A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 35-45 parts cement, 25-35 parts fly ash, 3-6 parts functional admixtures, 0.3-0.5 parts hydroxypropyl methylcellulose, 8-12 parts glass fiber absorbent, 4-6 parts hydrogen peroxide aqueous solution, and 15-20 parts water.

[0007] Furthermore, the fly ash is Class I fly ash.

[0008] Furthermore, the functional additive is magnesium oxide or aluminum oxide with a particle size of 0.1-1 μm.

[0009] Furthermore, the concentration of the hydrogen peroxide aqueous solution is 27-28%.

[0010] Furthermore, the glass fiber absorbent includes the following steps: Step 1: Take 1.4-1.8g of alkali-free glass fiber and add it to 200ml of ethyl acetate. Disperse it evenly by ultrasonication. Then add 0.42-0.72g of propyltriethoxysilane isocyanate and 0.02-0.03g of catalyst. Heat to 60-70℃ and stir continuously for 8-10h. After the reaction is completed, filter, wash and dry to obtain modified alkali-free glass fiber. Step 2: Take 1.2-1.4g of modified alkali-free glass fiber and add it to 100ml of ethanol aqueous solution. Disperse it evenly by ultrasonication to obtain a modified alkali-free glass fiber dispersion for later use. Take 0.6-0.7g of hyaluronic acid and add it to 50ml of deionized water. Stir evenly and then add the modified alkali-free glass fiber dispersion. Adjust the pH value to 3-4, heat to 50-60℃, stir at this temperature for 12-24h, filter, wash, and dry to obtain glass fiber absorbent.

[0011] Furthermore, in the first step, the mass ratio of the alkali-free glass fiber to propyltriethoxysilane is 1:0.3-0.4.

[0012] Furthermore, in the first step, the catalyst is dibutyltin dilaurate or stannous octoate.

[0013] Furthermore, in the first step, the alkali-free glass fiber has a length of 3-8 mm and a diameter of 10-15 μm.

[0014] Furthermore, in the second step, the volume fraction of the ethanol-water solution is 60-80%.

[0015] Through the above technical solution, the hydroxyl groups of alkali-free glass fiber and the isocyanate groups of propyltriethoxysilane undergo a carbamate reaction to introduce ethoxysilane groups. Then, the silanol produced by hydrolysis reacts with the hydroxyl groups of hyaluronic acid to obtain a glass fiber absorbent.

[0016] A method for preparing a heat pipe support includes the following steps: Step 1: Mix foamed cement, fly ash, functional admixtures, and hydroxypropyl methylcellulose until homogeneous. Then add glass fiber absorbent and continue mixing until homogeneous. Next, add water and mix for 20-30 minutes to form a homogeneous slurry. Finally, add hydrogen peroxide solution and sodium dodecyl sulfate and mix rapidly at 1100-1300 r / min for 2-5 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold and let it stand at 18-22℃ for 6-8 hours to foam. Then place it in a curing box and cure it at 24-26℃ and 90-92% humidity for 7-9 days to obtain the heat pipe support.

[0017] The beneficial effects of this invention are: (1) The thermal pipe support prepared by the present invention has excellent thermal insulation performance and high compressive strength by adjusting the base material ratio and adding functional additives and glass fiber absorbent.

[0018] (2) The mass ratio of foamed cement to fly ash is 1:0.71-0.78. By reasonably controlling the proportion of the base material, the balance between lightweight and load-bearing requirements is achieved. The prepared heat pipe support has a wide range of applications and meets diverse usage needs. In addition, foamed cement provides the core cementing effect and load-bearing foundation for the heat pipe support. Fly ash with a particle size of 14-16μm is selected, which can fill the pores of the matrix, improve the interface bonding performance, realize the resource utilization of industrial solid waste, significantly reduce production costs, and there is no emission of toxic and harmful substances throughout the preparation process, which is in line with the concept of green development.

[0019] (3) The functional additive is magnesium oxide with a fine particle size of 0.1-1μm. Magnesium oxide itself has excellent infrared radiation absorption and scattering ability. The fine particle size of 0.1-1μm further highlights its role. Under high temperature conditions, it can block the radiation heat transfer path, significantly reduce the high temperature thermal conductivity of the material, and ensure the thermal insulation stability. In addition, hydrogen peroxide decomposes to generate a large number of uniform bubbles. Sodium dodecyl sulfate reduces the gas-liquid interfacial tension to prevent the bubbles from agglomerating and breaking, and finally forms a closed-cell structure with a pore size of 50-300μm. It works synergistically with magnesium oxide to effectively suppress gas heat convection to optimize thermal insulation performance. It can effectively block heat transfer under both normal temperature and high temperature conditions, greatly improve the thermal insulation effect, and minimize the heat loss of the medium in the pipeline.

[0020] (4) Glass fiber water absorbent is prepared by grafting hyaluronic acid onto the surface of alkali-free glass fiber. The three-dimensional reinforcement structure formed by the alkali-free glass fiber in the matrix, combined with the optimization of the interfacial bonding performance by fly ash, significantly improves the compressive strength of the thermal tube support. At the same time, hyaluronic acid has excellent water absorption properties. In the process of preparing foamed cement, there is a problem of plastic shrinkage caused by the evaporation rate exceeding the rate at which water reaches the surface, which leads to plastic shrinkage cracks and a decrease in strength. However, hyaluronic acid stores a large amount of water, which is squeezed out during shrinkage deformation and slowly releases the water, effectively reducing the occurrence of plastic shrinkage and improving the strength of foamed cement.

[0021] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0023] A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 35 parts foamed cement, 25 parts Class I fly ash, 3 parts magnesium oxide with a particle size of 0.1 μm, 0.3 parts hydroxypropyl methylcellulose, 8 parts glass fiber absorbent, 4 parts hydrogen peroxide aqueous solution, and 15 parts water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Class I fly ash, magnesium oxide with a particle size of 0.1μm, and hydroxypropyl methylcellulose until uniform. Then add glass fiber absorbent and continue stirring until uniform. Add water and stir for 20 minutes to form a uniform slurry. Finally, add a 27% hydrogen peroxide aqueous solution and sodium dodecyl sulfate and stir rapidly at 1100 r / min for 2 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 18℃ for 6 hours to foam, and then put it into the curing box and cure it for 7 days at 24℃ and 90% humidity to obtain the heat pipe support.

[0024] The preparation method of the glass fiber absorbent includes the following steps: Step 1: Take 1.4g of alkali-free glass fiber with a length of 3mm and a diameter of 10μm and add it to 200ml of ethyl acetate. Disperse it evenly by ultrasonication. Then add 0.42g of propyltriethoxysilane isocyanate and 0.02g of dibutyltin dilaurate. Heat to 70℃ and stir continuously for 8h. After the reaction is completed, filter, wash and dry to obtain modified alkali-free glass fiber. Step 2: Take 1.2g of modified alkali-free glass fiber and add it to 100ml of 70% ethanol aqueous solution. Disperse it evenly by ultrasonication to obtain a modified alkali-free glass fiber dispersion for later use. Take 0.6g of hyaluronic acid and add it to 50ml of deionized water. Stir evenly and then add the modified alkali-free glass fiber dispersion. Adjust the pH value to 4, heat to 60℃, stir at this temperature for 12h, filter, wash, and dry to obtain glass fiber absorbent. Example 2

[0025] A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 36 parts foamed cement, 27 parts Class I fly ash, 5 parts magnesium oxide with a particle size of 0.5 μm, 0.4 parts hydroxypropyl methylcellulose, 11 parts glass fiber absorbent, 5 parts hydrogen peroxide aqueous solution, and 18 parts deionized water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Class I fly ash, magnesium oxide with a particle size of 0.5μm, and hydroxypropyl methylcellulose until uniform. Then add glass fiber absorbent and continue stirring until uniform. Add water and stir for 25 minutes to form a uniform slurry. Finally, add a 27.5% hydrogen peroxide aqueous solution and sodium dodecyl sulfate, and stir rapidly at 1200r / min for 3 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 20℃ for 7 hours to foam, and then put it into the curing box and cure it for 8 days at 25℃ and 91% humidity to obtain the heat pipe support. The preparation method of the glass fiber absorbent is the same as that in Example 1. Example 3

[0026] A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 45 parts foamed cement, 35 parts Class I fly ash, 6 parts magnesium oxide with a particle size of 1μm, 0.5 parts hydroxypropyl methylcellulose, 12 parts glass fiber absorbent, 6 parts hydrogen peroxide aqueous solution, and 20 parts deionized water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Class I fly ash, magnesium oxide with a particle size of 1μm, and hydroxypropyl methylcellulose until uniform. Then add glass fiber absorbent and continue stirring until uniform. Add water and stir for 30 minutes to form a uniform slurry. Finally, add a 28% hydrogen peroxide aqueous solution and sodium dodecyl sulfate and stir rapidly at 1300 r / min for 5 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 22℃ for 8 hours to foam, and then put it into the curing box and cure it for 9 days at 26℃ and 92% humidity to obtain the heat pipe support. The preparation method of the glass fiber absorbent is the same as that in Example 1.

[0027] Comparative Example 1 A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 36 parts foamed cement, 27 parts Class I fly ash, 0.4 parts hydroxypropyl methylcellulose, 11 parts glass fiber absorbent, 5 parts hydrogen peroxide aqueous solution, and 18 parts deionized water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Class I fly ash, and hydroxypropyl methylcellulose until uniform. Then add glass fiber absorbent and continue mixing until uniform. Add water and mix for 25 minutes to form a uniform slurry. Finally, add a 27.5% hydrogen peroxide aqueous solution and sodium dodecyl sulfate and mix rapidly at 1200 r / min for 3 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 20℃ for 7 hours to foam, and then put it into the curing box and cure it for 8 days at 25℃ and 91% humidity to obtain the heat pipe support. The preparation method of the glass fiber absorbent is the same as that in Example 1.

[0028] Comparative Example 2 A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 36 parts foamed cement, 27 parts Class I fly ash, 5 parts magnesium oxide with a particle size of 0.5 μm, 0.4 parts hydroxypropyl methylcellulose, 11 parts alkali-free glass fiber, 5 parts hydrogen peroxide aqueous solution, and 18 parts deionized water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Grade I fly ash, magnesium oxide with a particle size of 0.5μm, and hydroxypropyl methylcellulose until uniform. Then add alkali-free glass fiber and continue stirring until uniform. Add water and stir for 25 minutes to form a uniform slurry. Finally, add a 27.5% hydrogen peroxide aqueous solution and sodium dodecyl sulfate, and stir rapidly at 1200r / min for 3 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 20℃ for 7 hours to foam, and then put it into the curing box and cure it for 8 days at 25℃ and 91% humidity to obtain the heat pipe support. The difference between Comparative Example 2 and Example 1 is that alkali-free glass fiber is used instead of glass fiber absorbent, while the rest are the same.

[0029] Comparative Example 3 A high-performance, low-thermal-conductivity heat pipe support comprises the following raw materials in parts by weight: 36 parts foamed cement, 27 parts Class I fly ash, 5 parts magnesium oxide with a particle size of 0.5 μm, 0.4 parts hydroxypropyl methylcellulose, 5 parts hydrogen peroxide aqueous solution, and 18 parts deionized water; The manufacturing process of the thermal tube trailer includes the following steps: Step 1: Mix foamed cement, Class I fly ash, magnesium oxide with a particle size of 0.5μm, and hydroxypropyl methylcellulose. Stir until uniform, then add water and stir for 25 minutes to form a uniform slurry. Finally, add a 27.5% hydrogen peroxide aqueous solution and sodium dodecyl sulfate, and stir rapidly at 1200r / min for 3 minutes to obtain the pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold, let it stand at 20℃ for 7 hours to foam, and then put it into the curing box and cure it for 8 days at 25℃ and 91% humidity to obtain the heat pipe support.

[0030] Performance testing The pre-foamed slurries from Examples 1-3 and Comparative Examples 1-3 were injected into cylindrical molds with a diameter of 0.4m and cubic molds with a side length of 100mm, respectively. They were allowed to stand and foam for 7 hours at 20°C, and then placed in a curing chamber and cured for 8 days at 25°C and 91% humidity to produce test samples that met the requirements of each test.

[0031] The compressive strength was tested according to standard GB / T 5486-2008 "Test Methods for Inorganic Rigid Thermal Insulation Products"; Thermal conductivity was tested according to standard GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials - Protective Hot Plate Method".

[0032] The results are shown in the table below: According to the compressive strength data, the glass fiber absorbent added in the example can significantly improve the compressive strength of the thermoplastic cement. This is because the three-dimensional reinforcing structure formed by the alkali-free glass fiber in the matrix, combined with the optimization of the interfacial bonding performance by fly ash, significantly enhances the compressive strength. At the same time, hyaluronic acid has excellent water absorption properties. It is squeezed out during shrinkage deformation and releases water, effectively reducing the occurrence of plastic shrinkage and improving the strength of foamed cement.

[0033] The thermal conductivity data shows that the embodiment has excellent heat preservation effect because the added magnesium oxide has excellent infrared radiation absorption and scattering ability. Under high temperature conditions, it can block the radiation heat transfer path, significantly reduce the high temperature thermal conductivity of the material, and ensure the thermal insulation stability. In addition, hydrogen peroxide and sodium dodecyl sulfate work together to form uniform bubbles that are not easy to agglomerate and break. They work synergistically with magnesium oxide to effectively suppress gas heat convection to optimize thermal insulation performance. Moreover, it can effectively block heat transfer under both normal and high temperature conditions, greatly improving the thermal insulation effect and minimizing the heat loss of the medium in the pipeline.

[0034] The above content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the scope defined by the inventive concept, they should all fall within the protection scope of the present invention.

Claims

1. A high-performance, low-thermal-conductivity heat pipe support, characterized in that, Including the following parts by weight of raw materials: 35-45 parts cement, 25-35 parts fly ash, 3-6 parts functional admixtures, 0.3-0.5 parts hydroxypropyl methylcellulose, 8-12 parts glass fiber absorbent, 4-6 parts hydrogen peroxide aqueous solution, and 15-20 parts water.

2. The high-performance, low-thermal-conductivity heat pipe support according to claim 1, characterized in that, The fly ash is Class I fly ash.

3. The high-performance, low-thermal-conductivity heat pipe support according to claim 1, characterized in that, The functional additive is magnesium oxide or aluminum oxide with a particle size of 0.1-1 μm.

4. The high-performance, low-thermal-conductivity heat pipe support according to claim 1, characterized in that, The concentration of the hydrogen peroxide aqueous solution is 27-28%.

5. A high-performance, low-thermal-conductivity heat pipe support according to claim 1, characterized in that, The preparation method of the glass fiber absorbent includes the following steps: Step 1: Add alkali-free glass fiber to ethyl acetate, ultrasonically disperse it evenly, add propyltriethoxysilane isocyanate and catalyst, heat to 60-70℃, and stir continuously for 8-10 hours. After the reaction is completed, filter, wash and dry to obtain modified alkali-free glass fiber. Step 2: Add modified alkali-free glass fiber to an ethanol aqueous solution and ultrasonically disperse it evenly to obtain a modified alkali-free glass fiber dispersion for later use; add hyaluronic acid to deionized water and stir evenly, then add the modified alkali-free glass fiber dispersion, adjust the pH value to 3-4, heat to 50-60℃, stir at this temperature for 12-24 hours, filter, wash, and dry to obtain glass fiber absorbent.

6. A high-performance, low-thermal-conductivity heat pipe support according to claim 5, characterized in that, In the first step, the mass ratio of the alkali-free glass fiber to propyltriethoxysilane is 1:0.3-0.

4.

7. A high-performance, low-thermal-conductivity heat pipe support according to claim 5, characterized in that, In the first step, the catalyst is dibutyltin dilaurate or stannous octoate.

8. A high-performance, low-thermal-conductivity heat pipe support according to claim 5, characterized in that, In the first step, the alkali-free glass fiber has a length of 3-8 mm and a diameter of 10-15 μm.

9. A high-performance, low-thermal-conductivity heat pipe support according to claim 5, characterized in that, In the second step, the volume fraction of the ethanol aqueous solution is 60-80%.

10. A manufacturing process for a high-performance, low-thermal-conductivity heat pipe support as described in claim 1, characterized in that, Includes the following steps: Step 1: Mix foamed cement, fly ash, functional admixture, and hydroxypropyl methylcellulose until uniform. Then add glass fiber absorbent and continue mixing until uniform. Add water and mix for 20-30 minutes to form a uniform slurry. Finally, add hydrogen peroxide solution and sodium dodecyl sulfate and mix rapidly at 1100-1300 r / min for 2-5 minutes to obtain pre-foamed slurry. Step 2: Inject the pre-foamed slurry into the mold and let it stand at 18-22℃ for 6-8 hours to foam. Then place it in a curing box and cure it at 24-26℃ and 90-92% humidity for 7-9 days to obtain the heat pipe support.

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