Aerogel composite thermal insulation material, preparation method thereof and application of aerogel composite thermal insulation material in LNG (Liquefied Natural Gas) ship

Abstract

The invention provides an aerogel composite thermal insulation material, a preparation method thereof and application of the aerogel composite thermal insulation material in LNG ships, and relates to the technical field of aerogel composite materials for ships, the aerogel composite thermal insulation material comprises a thermal insulation layer, the thermal insulation layer is formed by crosslinking SiO2 aerogel particles, polyimide nanofibers and a fluorine-containing silane coupling agent, the thermal insulation layer is internally provided with a porous structure, and the aerogel composite thermal insulation material is prepared from the aerogel particles, the polyimide nanofibers and the fluorine-containing silane coupling agent. The porosity is 88-95%, and the average pore size is 20-50 nm; the reinforced supporting layer is a metal grid formed by a plurality of polygonal structures, the heat insulation layer is embedded into the metal grid to form a composite heat insulation layer, and the polygonal structures are quadrangular; the buffer layer is arranged outside the composite heat insulation layer; and the fixing structure is arranged outside the buffer layer. The aerogel composite thermal insulation material has excellent thermal insulation performance, cryogenic vibration resistance and strong weather resistance, and is suitable for cold insulation systems of LNG ship cargo holds and related low-temperature storage and transportation equipment.

Description

Technical Field

[0001] This invention relates to the field of marine aerogel composite materials technology, and in particular to an aerogel composite thermal insulation material, its preparation method, and its application in LNG ships. Background Technology

[0002] The storage and transportation of liquefied natural gas (LNG) relies on LNG carriers, whose cargo holds need to be maintained at an ultra-low temperature of -163°C for a long time. In addition, the ships face harsh conditions such as high-frequency vibration of 10-200 Hz and marine salt spray corrosion during navigation. Therefore, the performance of cargo hold insulation materials directly determines the safety and economy of LNG transportation.

[0003] The following key defects exist in the current cold insulation materials used in the industry: (1) Performance bottleneck of traditional cold insulation materials: Polyurethane foam (PIR): thermal conductivity ≥0.025 W / (m·K), low heat insulation efficiency, resulting in increased LNG evaporation loss rate; and in the -163℃ cryogenic environment, the molecular chain becomes brittle, the compressive strength drops to ≤0.3 MPa, and it is prone to cracking under high frequency vibration, requiring frequent maintenance. Vacuum insulation panel (VIP): Although the thermal conductivity is low (≈0.015 W / (m·K)), the core material (such as glass fiber, fumed silica) is prone to settling under long-term vibration, resulting in the destruction of the vacuum degree inside the panel and failure of the heat insulation performance (usually needs to be replaced every 1-2 years), and cannot be adapted to the complex curved surface of LNG ship cargo hold. (2) Limitations of existing aerogel materials: Pure SiO2 aerogel is considered an ideal low-temperature insulation material due to its thermal conductivity ≤0.014 W / (m·K), but it has three major problems in the LNG ship scenario: Significant cryogenic brittleness: The compressive strength at -163℃ is ≤0.5 MPa, the elongation at break is only 2%, and it is easy to break and delaminate under high frequency vibration, and cannot withstand the dynamic load during ship navigation; Poor hydrophobic stability: The surface hydroxyl groups are easy to combine with water vapor in marine salt spray, and the thermal conductivity increases by more than 30% after absorbing water, which will cause the core material structure to collapse; Low construction adaptability: Existing aerogel products are mostly rolls or flat sheets, which need to be cut and spliced ​​on site. The gap treatment depends on sealant (the construction efficiency is only 5-8 m² / day), and the splice is prone to gaps due to vibration, resulting in excessive heat leakage rate (which cannot meet the heat leakage requirement of ≤0.5 W / (m²·K) for LNG ships).

[0004] In view of this, it is necessary to design an improved aerogel composite insulation material, its preparation method, and its application in LNG ships to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to provide an aerogel composite insulation material, its preparation method, and its application in LNG ships.

[0006] To achieve the above-mentioned objectives, in a first aspect, the present invention provides an aerogel composite thermal insulation material, comprising:

[0007] The heat insulation layer is formed by cross-linking SiO2 aerogel particles, polyimide nanofibers and fluorinated silane coupling agent. The heat insulation layer has a porous structure with a porosity of 88-95% and an average pore size of 20-50 nm.

[0008] The reinforcing support layer is a metal mesh formed by several polygonal structures, and the heat insulation layer is embedded in the metal mesh to form a composite heat insulation layer. The polygonal structures are quadrilaterals.

[0009] A buffer layer is disposed outside the composite insulation layer;

[0010] A fixed structure is disposed outside the buffer layer.

[0011] Preferably, the buffer layer is a low-temperature resistant addition-cured silicone rubber film with a thickness of 0.5-1 mm and the following performance parameters: Shore A hardness 50-60, elongation at break ≥200% at -196℃, and water vapor permeability ≤0.1 g / (m²·24h).

[0012] Preferably, the fixing structure is a cuboid with grooves and protrusions, the grooves and protrusions being respectively disposed on two opposite sides of the cuboid, and the interior of the fixing structure having a quadrilateral cavity for accommodating the heat insulation layer, the reinforcing support layer and the buffer layer.

[0013] Preferably, the width of the protrusion is 7-9 mm, the depth of the groove is 6-8 mm, and the width of the groove is the same as the width of the protrusion.

[0014] Secondly, the present invention provides a method for preparing an aerogel composite thermal insulation material, comprising the following steps:

[0015] SiO2 aerogel particles and polyimide nanofibers were added to a dispersion and dispersed evenly. Then, a coupling agent was added and mixed evenly to obtain a modified SiO2 aerogel particle slurry.

[0016] After the modified SiO2 aerogel particle slurry is poured into the pretreated reinforcing support layer, it undergoes degassing and cross-linking curing. The modified SiO2 aerogel particle slurry fills the metal mesh of the reinforcing support layer and is cured to form a heat insulation layer. The heat insulation layer and the reinforcing support layer together form a composite heat insulation layer.

[0017] Low-temperature resistant silicone rubber emulsion is sprayed onto the surface of the composite insulation layer to form a buffer layer; finally, the resulting material is placed as a whole in the cavity of the fixed structure.

[0018] Preferably, the SiO2 aerogel particles have a particle size of 5-10 μm, a thermal conductivity of 0.012-0.013 W / (m·K), and a hydrophobic angle ≥145°; the coupling agent is a tridecafluorooctyltriethoxysilane solution with a mass fraction of 8-12%, and the mixing process after adding the coupling agent is carried out under ultrasonic conditions with an ultrasonic power of 500-600 W and a time of 30-40 min.

[0019] Preferably, the mass ratio of the SiO2 aerogel particles to the polyimide nanofibers is 7:3-9:1; the polyimide nanofibers have a diameter of 200-300 nm, a length of 50-100 μm, and a tensile strength ≥800 MPa, and are prepared by electrospinning with the following spinning parameters: voltage 25-30 kV, flow rate 0.5-1 mL / h, receiving distance 15-20 cm, and imidization at 300℃ for 2 h after spinning.

[0020] Preferably, before crosslinking and curing, the sample obtained by degassing treatment needs to be subjected to low-temperature treatment, which is to pre-freeze at -50℃ to -60℃ for 12-15h, with a cooling rate of 5℃ / h. Crosslinking and curing are carried out by segmented thermal crosslinking at 60-80℃ and a vacuum degree of -0.08 to -0.09 MPa to achieve curing.

[0021] Preferably, the segmented thermal crosslinking is carried out as follows: initial crosslinking is performed by holding at 60°C for 8 hours, followed by deep crosslinking by holding at 70°C for 12 hours, and finally, the temperature is maintained at 80°C for 4-10 hours, with a total curing time of 24-30 hours.

[0022] Thirdly, the present invention provides an application of aerogel composite insulation material in LNG ships.

[0023] The beneficial effects of this invention are:

[0024] 1. The preparation method of the aerogel composite insulation material provided by the present invention involves first preparing a heat insulation layer by cross-linking SiO2 aerogel particles, polyimide nanofibers and fluorinated silane coupling agents, and then further preparing an aerogel composite insulation material with a layered structure, ultimately obtaining an aerogel composite insulation material with excellent heat insulation performance, cryogenic vibration resistance, strong weather resistance, and suitable for the cold insulation system of LNG ship cargo holds and related cryogenic storage and transportation equipment.

[0025] 2. The aerogel composite insulation material provided by this invention has a thermal conductivity as low as 0.010~0.013 W / (m·K), a compressive strength of ≥0.9 MPa at -163℃, no delamination after 100 h of vibration at 10~200Hz, a hydrophobic angle retention rate of ≥90% after 5000 h of salt spray testing, a water vapor permeability of ≤0.1 g / (m²·24 h), and a construction efficiency of 20-25 m² / day. It can also meet the requirements of aerogel composite insulation materials for the special application environment of LNG ships, which is characterized by "deep cooling, vibration, and salt spray". Attached Figure Description

[0026] Figure 1 This is a top view of the overall structure of the aerogel composite thermal insulation material proposed in this invention;

[0027] Figure 2 This is a cross-sectional view of the overall structure of the aerogel composite thermal insulation material proposed in this invention;

[0028] Figure 3 This is a schematic diagram of the overall structure of the aerogel composite thermal insulation material proposed in this invention;

[0029] Figure 4 The formation mechanism of the thermal insulation layer 1 of the aerogel composite thermal insulation material proposed in this invention;

[0030] The attached figures are labeled as follows:

[0031] 1. Insulation layer; 2. Reinforcing support layer; 3. Buffer layer; 4. Fixing structure; 41. Protrusion; 42. Groove. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0034] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0035] On the one hand, please refer to Figure 1-3 As shown, the present invention provides an aerogel composite thermal insulation material, comprising:

[0036] The heat insulation layer 1 is formed by cross-linking SiO2 aerogel particles, polyimide nanofibers and fluorinated silane coupling agent. The layer has a porous structure with a porosity of 88-95% and an average pore size of 20-50 nm.

[0037] The reinforcing support layer 2 is a metal mesh formed by several polygonal structures. The heat insulation layer 1 is embedded in the metal mesh of the reinforcing support layer 2. The heat insulation layer 1 and the reinforcing support layer 2 together serve as a composite heat insulation layer 1. The polygonal structure is preferably quadrilateral with a wire diameter of 0.1-0.2 mm and a pore size of 3-5 mm.

[0038] Buffer layer 3 is disposed outside the composite insulation layer 1;

[0039] Fixed structure 4 is located outside the buffer layer 3.

[0040] In some embodiments, the buffer layer 3 is specifically a low-temperature resistant (-196℃) addition-cured silicone rubber film (model: XIAMETER® RBB-2060-50), with a thickness of 0.5-1mm, and its performance parameters are as follows: Shore A hardness 50-60, elongation at break at -196℃ ≥200%, and water vapor permeability ≤0.1 g / (m²·24h). By setting this structural layer, the low-temperature flexibility of the silicone rubber film can be used to buffer vibration impact, and it can also serve as a water vapor barrier layer to prevent salt spray and water vapor from penetrating into the heat insulation layer 1. In some embodiments, the fixing structure 4 is a cuboid with a groove 42 and a protrusion 41, which are respectively disposed on two opposite sides of the cuboid. The interior of the fixing structure 4 has a quadrilateral cavity for accommodating the heat insulation layer 1, the reinforcing support layer 2, and the buffer layer 3, as shown in the figure. Figure 3 As shown, the width of the protrusion 41 is 7-9 mm, and the depth of the groove 42 is 6-8 mm, with the same width as the protrusion 41. When several aerogel composite insulation materials need to be spliced ​​together, the splicing can be achieved by utilizing the interlocking between the protrusion 41 and the groove 42 of the fixing structure 4 for several composite insulation materials. In particular, to prevent movement between two adjacent composite insulation materials, an expansion sealing strip can be added to the contact surface between the groove 42 and the protrusion 41, preferably on the side of the protrusion 41 away from the cuboid. Specifically, the shrinkage rate of the expansion sealing strip at -163℃ is ≤1%, and the gap after splicing is ≤0.3 mm (i.e., the horizontal distance between the groove 42 and the protrusion 41 after the groove 42 is inserted into the protrusion 41). By designing the composite insulation material into a splicing pattern, different sizes and shapes of insulation layers can be obtained by selecting the required number of composite insulation materials to splice together according to the needs of different application scenarios. The expansion sealing strip is filled between two adjacent composite insulation materials, which can take advantage of its non-shrinkage property at low temperatures to fill the gaps at the splicing parts and achieve the purpose of insulation.

[0041] In some embodiments, the preparation method of modified SiO2 aerogel particle slurry includes the following steps:

[0042] SiO2 aerogel particles and polyimide nanofibers were added to a dispersion and dispersed evenly. Then, a coupling agent was added and mixed evenly to obtain a modified SiO2 aerogel particle slurry.

[0043] Specifically, the SiO2 aerogel particles have a particle size of 5-10 μm, a thermal conductivity of 0.012-0.013 W / (m·K), and a hydrophobic angle ≥145°. The polyimide nanofibers have a diameter of 200-300 nm, a length of 50-100 μm, and a tensile strength ≥800 MPa. They are prepared by electrospinning with the following parameters: voltage 25-30 kV, flow rate 0.5-1 mL / h, and receiving distance 15-20 cm. After spinning, the nanofibers are imidized at 300℃ for 2 h. The dispersion is obtained by mixing ethanol (purity ≥99.5%) and water at a volume ratio of 3:1. The dispersion process is carried out under stirring conditions at a stirring rate of 500-800 rpm for 10-15 min. The mass ratio of SiO2 aerogel particles to polyimide nanofibers is 7:3-9:1. The coupling agent accounts for 3-5% of the mass of the slurry. It is a solution of tridecafluorooctyltriethoxysilane with a mass fraction of 8-12%. The solvent is ethanol (analytical grade) and water mixed in a volume ratio of 3:1. The mixing process after adding the coupling agent is carried out under ultrasonic conditions with an ultrasonic power of 500-600 W and a time of 30-40 min.

[0044] In the above technical solution, modified SiO2 aerogel particle slurry is prepared by utilizing the cross-linking effect of SiO2 aerogel particles, polyimide nanofibers and fluorinated silane coupling agents. The polyimide nanofibers provide a "fiber skeleton" for the aerogel, increasing the elongation at break from 2% of pure aerogel to 15%. The fluorocarbon chains of the fluorinated silane coupling agent modify the surface of the aerogel to form a superhydrophobic layer, resisting salt spray and water vapor. At the same time, chemical cross-linking of the aerogel and fibers is achieved through Si-O-Si bonds, avoiding particle agglomeration.

[0045] Furthermore, the present invention also provides a method for preparing the above-mentioned aerogel composite thermal insulation material, comprising the following steps:

[0046] After the modified SiO2 aerogel particle slurry is poured into the pretreated reinforcing support layer 2, it is degassed and cross-linked and cured. The modified SiO2 aerogel particle slurry is then cured and formed in the metal mesh of the reinforcing support layer 2. Low-temperature resistant silicone rubber emulsion is sprayed onto the surface of the obtained sample to form a buffer layer 3. Finally, the obtained material is placed in the cavity of the fixed structure 4.

[0047] In some embodiments, the pretreatment of the reinforcing support layer 2 is performed as follows: the reinforcing support layer 2 is ultrasonically cleaned in 5% dilute hydrochloric acid for 10 min to remove the surface oxide layer, and then dried at 120℃ for 2 h to activate the surface hydroxyl groups, thus obtaining the pretreated reinforcing support layer 2. Through a vacuum impregnation process (the reinforcing support layer 2 is placed in a vacuum drying oven, maintained at a vacuum degree of -0.08~-0.09 MPa for 15 min; slurry is added to a depth 2-3 mm above the mesh, maintained at the same vacuum degree for another 20 min, and after restoring normal pressure, the slurry is leveled (error ≤ 0.3 mm)), the hydroxyl groups (activated by pretreatment) on the surface of the stainless steel micromesh react with the Si-OH bonds of the SiO2 aerogel in the core insulation layer 1 to form Si-O-Si covalent bonds, increasing the compressive strength under cryogenic conditions from 0.5 MPa of pure aerogel to ≥0.9 MPa, while simultaneously dispersing vibration loads and avoiding cracking caused by localized stress concentration.

[0048] In some embodiments, the sample obtained from the degassing treatment needs to be subjected to low-temperature treatment before crosslinking and curing. The low-temperature treatment, degassing treatment, and crosslinking and curing are carried out according to the following steps: First, the slurry is degassed at 0.09 MPa for 20-30 min to remove air bubbles. Then, it is pre-frozen at -50℃ to -60℃ for 12-15 h. The rate of temperature drop from room temperature to the target temperature during the pre-freezing process is 5℃ / h. This cooling rate can avoid excessively large ice crystals that could damage the porous structure of the slurry. Next, segmented thermal crosslinking is carried out at 60-80℃ and a vacuum of -0.08 to -0.09 MPa to complete the crosslinking and curing. The segmented thermal crosslinking is carried out as follows: initial crosslinking is performed at 60℃ for 8 h, followed by deep crosslinking at 70℃ for 12 h, and finally, it is performed at 80℃ for 4-10 h, with a total curing time of 24-30 h. During the curing process, the ethoxy group (-OC2H5) of tridecafluorooctyltriethoxysilane undergoes a hydrolytic condensation reaction with the hydroxyl groups (-OH) on the aerogel surface, forming Si-O-Si covalent bonds. This achieves the chemical bonding of the SiO2 aerogel, polyimide nanofibers, and the metal mesh of the reinforcing support layer 2. The specific crosslinking mechanism is as follows: Figure 4 As shown.

[0049] In some embodiments, the low-temperature resistant silicone rubber emulsion comprises the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity range 5000-8000 mPa·s), 8-12 parts of hydrogen-containing polysiloxane (hydrogen content 0.18-0.22%, used as a crosslinking agent to undergo an addition reaction with the vinyl-terminated polydimethylsiloxane), 0.3-0.5 parts of chloroplatinic acid-vinylsiloxane complex (concentration 1000 ppm, catalyzing the crosslinking reaction to control the curing rate), 5-8 parts of polymethylphenylsiloxane (phenyl content 15-20%, lowering the glass transition temperature of silicone rubber to improve cryogenic resistance), 15-20 parts of hexamethyldisilazane-modified fumed silica (specific surface area 200-300 m² / g, enhancing the mechanical strength and abrasion resistance of the cured emulsion), and 2-3 parts of a 10% by weight fraction. The mixture consists of a perfluorooctyltriethoxysilane ethanol solution (to enhance the hydrophobicity and salt spray resistance of buffer layer 3 after emulsion curing), 150-200 parts of anhydrous ethanol-ethyl acetate mixed solvent (volume ratio 3:1 to ensure uniform dispersion of each component), and 0.5-1 parts of diphenylsilanediol (to inhibit self-crosslinking during emulsion storage to improve stability). The solid content is 30-40%, the spraying thickness is 0.5-1 mm, and the coating is dried at 25-30℃ for 2-3 h after spraying to form buffer layer 3.

[0050] The following specific embodiments further illustrate the aerogel composite insulation material, its preparation method, and its application in LNG ships provided by the present invention:

[0051] Example 1

[0052] This embodiment provides a method for preparing an aerogel composite thermal insulation material with dimensions of length × width × height = 1000mm × 500mm × 30mm. The specific steps are as follows:

[0053] 800g of SiO2 aerogel particles and 200g of polyimide nanofibers were weighed and added to a mixture of 10L ethanol and water (ethanol and water were mixed at a volume ratio of 3:1). The mixture was stirred at 500rpm for 12min to form a preliminary dispersion. Then, 400g of a 10% (w / w) tridecafluorooctyltriethoxysilane solution (using the aforementioned ethanol and water mixture as the solvent) was added and the mixture was ultrasonically dispersed at 500W for 35min. The particle size distribution of the slurry was measured using a laser particle size analyzer (D50 = 12μm, no agglomeration), thus obtaining a modified SiO2 aerogel particle slurry. The SiO2 aerogel particles had a particle size of 5-10μm and a thermal conductivity of 0.012-0.013. W / (m・K), hydrophobic angle ≥145°; polyimide nanofibers were prepared by electrospinning with pyromellitic dianhydride (PMDA) and 4,4'-diaminodiphenyl ether (ODA) as monomers and N,N-dimethylacetamide (DMAc) as solvent. The wet nanofibers were prepared under the conditions of 28kV voltage, 0.8mL / h flow rate, and 18cm receiving distance, and then imidized at 300℃ for 2h. The polyimide nanofibers had a diameter of 200-300nm, a length of 50-100μm, and a tensile strength ≥800MPa.

[0054] The modified SiO2 aerogel particle slurry was poured into a pretreated 316L stainless steel microgrid (1020mm × 520mm). The grid was laid flat at the bottom of a polytetrafluoroethylene mold (length × width × height = 1020mm × 520mm × 45mm). The modified SiO2 aerogel particle slurry was poured in, and the surface was leveled with a scraper (surface error ≤ 0.3mm). The mold and grid were then subjected to degassing treatment at -0.09MPa for 25 minutes. The sample was transferred to a -55℃ low-temperature chamber and cooled to -55℃ at a rate of 5℃ / h, and kept at this temperature for 12 hours for pre-freezing. Then, at -0.08MPa, it was cured by segmented thermal cross-linking as follows: first, kept at 60℃ for 8 hours, then at 70℃ for 12 hours, and finally at 80℃ for 8 hours to complete the curing. Samples were taken to test the interfacial bonding strength using a universal testing machine (according to GB / T16777). The measured interfacial bonding strength was 1.3MPa (meeting the requirement of ≥1.2MPa).

[0055] A low-temperature resistant silicone rubber emulsion with a solid content of 30-40% is sprayed onto the surface of the cured material to a thickness of 0.8 mm. The emulsion is then dried at 25°C for 2.5 hours to form a buffer layer. More specifically, the low-temperature resistant silicone rubber emulsion comprises the following raw materials in parts by weight: 100 parts of vinyl-terminated polydimethylsiloxane (viscosity range 5000-8000 mPa·s), 10 parts of hydrogen-containing polysiloxane (hydrogen content 0.20%, used as a crosslinking agent to undergo an addition reaction with the vinyl-terminated polydimethylsiloxane), 0.40 parts of chloroplatinic acid-vinylsiloxane complex (concentration 1000 ppm, catalyzing the crosslinking reaction to control the curing rate), 6 parts of polymethylphenylsiloxane (phenyl content 16%, lowering the glass transition temperature of silicone rubber to improve cryogenic resistance), and 18 parts of hexamethyldisilazane-modified fumed silica (specific surface area 260). m² / g, to enhance the mechanical strength and abrasion resistance of the cured emulsion; 2 parts by mass of 10% perfluorooctyltriethoxysilane ethanol solution (to improve the hydrophobicity and salt spray resistance of the buffer layer after emulsion curing); 160 parts of anhydrous ethanol-ethyl acetate mixed solvent (volume ratio 3:1 to ensure uniform dispersion of each component); and 0.5 parts of diphenylsilanediol (to inhibit self-crosslinking during emulsion storage to improve stability).

[0056] The material forming the buffer layer is embedded in the quadrilateral cavity of the fixing structure. The fixing structure is a cuboid with grooves and protrusions, located on two opposite sides of the cuboid. The protrusions are 8mm wide, and the grooves are 7mm deep, with the same width as the protrusions. Specifically, if multiple composite insulation materials need to be joined, this can be achieved by interlocking the protrusions and grooves of the fixing structures of several composite insulation materials. To prevent movement between adjacent composite insulation materials, an expansion sealing strip can be added to the contact surface between the groove and the protrusion. The expansion sealing strip has a shrinkage rate ≤1% at -163℃, and the gap after splicing is ≤0.3mm.

[0057] It should be noted that in other embodiments, the dimensions of the aerogel composite insulation material can also be adjusted according to the actual application requirements, and this is not a limitation here.

[0058] Examples 2 to 3

[0059] The only difference between Examples 2 and 3 and Example 1 is the specific process parameters and the dimensions of the composite insulation material. All other experimental parameters are the same as in Example 1 and will not be repeated here. The process parameters for Examples 1 to 3 are shown in Table 1, where the curing temperature is the temperature of the second stage of segmented thermal crosslinking curing.

[0060] Table 1. Process parameters and performance results of the obtained composite insulation materials in Examples 1 to 3.

[0061]

[0062] Examples 4 to 5

[0063] The only difference between Examples 4 and 5 and Example 1 is the mass ratio of aerogel particles to fibers. In Example 4, the mass ratio of aerogel particles to fibers is 7:3, and in Example 5, it is 9:1. All other experimental parameters are the same as in Example 1 and will not be repeated here. The performance results of the composite insulation materials prepared in Examples 1 and Examples 4 to 5 are shown in Table 2. The results show that although Example 1 exhibits good overall performance, its tensile strength is significantly lower than that of Example 4. Although Example 5 has the best thermal insulation performance compared to other examples, its tensile strength is the lowest, and it developed cracks during vibration testing, posing a risk in application. Example 4 has higher low-temperature tensile strength, vibration stability, and long-term corrosion resistance compared to Examples 1 and 5. The performance advantage of Example 4 lies in its core mechanism: a 7:3 mass ratio of aerogel particles to fibers. This ratio achieves optimal three-dimensional synergy between thermal insulation, mechanical support, and weather-resistant cross-linking. The 30% polyimide nanofibers form a continuous three-dimensional flexible skeleton between the aerogel particles, with a high density of interlacing points. This effectively disperses cryogenic shrinkage stress at -163℃ and multi-frequency vibration impact stress, preventing localized cracking, while also absorbing vibration energy through its flexibility under cryogenic conditions. It should be noted that the retention rate in this article refers to the ratio of the remaining value of a certain hydrophobic angle property to its initial value after 5000 hours of salt spray testing. It reflects the material's ability to maintain hydrophobic properties under long-term salt spray conditions. A higher retention rate indicates stronger weather resistance and better suitability for the use of LNG ships in marine environments.

[0064] Table 2 Performance of the composite thermal insulation materials prepared in Examples 1 and 4 to 5

[0065]

[0066] Comparative Example 1

[0067] The only difference between Comparative Example 1 and Example 1 is that the polyimide nanofibers are omitted, and 800g of SiO2 aerogel particles are directly prepared into aerogel particle slurry, which is then further processed into a composite thermal insulation material. The process parameters of the preparation process are the same as those of Example 1, and will not be repeated here. The polyurethane foam is specifically Elastopir® Blue rigid polyurethane foam board.

[0068] The performance results of the aerogel composite insulation materials prepared in Example 1 and Comparative Example 1 are shown in Table 3. The results show that the performance of the composite insulation material prepared in Example 1 is better than that of Comparative Example 1 and traditional polyurethane foam insulation materials.

[0069] Table 3 Performance results of the aerogel composite thermal insulation material prepared in Example 1

[0070]

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An aerogel composite thermal insulation material, characterized in that, include: The heat insulation layer is formed by cross-linking SiO2 aerogel particles, polyimide nanofibers and fluorinated silane coupling agent. The heat insulation layer has a porous structure with a porosity of 88-95% and an average pore size of 20-50 nm. The reinforcing support layer is a metal mesh formed by several polygonal structures, and the heat insulation layer is embedded in the metal mesh to form a composite heat insulation layer. The polygonal structures are quadrilaterals. A buffer layer is disposed outside the composite insulation layer; A fixed structure is disposed outside the buffer layer.

2. The aerogel composite thermal insulation material according to claim 1, characterized in that, The buffer layer is a low-temperature resistant addition-cured silicone rubber film with a thickness of 0.5-1 mm and the following performance parameters: Shore A hardness 50-60, elongation at break ≥200% at -196℃, and water vapor permeability ≤0.1 g / (m²·24h).

3. The aerogel composite thermal insulation material according to claim 1, characterized in that, The fixing structure is a cuboid with grooves and protrusions, the grooves and protrusions being respectively disposed on two opposite sides of the cuboid. The interior of the fixing structure has a quadrilateral cavity for accommodating the heat insulation layer, the reinforcing support layer, and the buffer layer.

4. The aerogel composite thermal insulation material according to claim 3, characterized in that, The width of the protrusion is 7-9mm, and the depth of the groove is 6-8mm, with the same width as the protrusion.

5. A method for preparing an aerogel composite thermal insulation material according to any one of claims 1-4, characterized in that, Includes the following steps: SiO2 aerogel particles and polyimide nanofibers were added to a dispersion and dispersed evenly. Then, a coupling agent was added and mixed evenly to obtain a modified SiO2 aerogel particle slurry. After the modified SiO2 aerogel particle slurry is poured into the pretreated reinforcing support layer, it undergoes degassing and cross-linking curing. The modified SiO2 aerogel particle slurry fills the metal mesh of the reinforcing support layer and is cured to form a heat insulation layer. The heat insulation layer and the reinforcing support layer together form a composite heat insulation layer. Low-temperature resistant silicone rubber emulsion is sprayed onto the surface of the composite insulation layer to form a buffer layer; finally, the resulting material is placed as a whole in the cavity of the fixed structure.

6. The preparation method according to claim 5, characterized in that, The SiO2 aerogel particles have a particle size of 5-10 μm, a thermal conductivity of 0.012-0.013 W / (m·K), and a hydrophobic angle ≥145°. The coupling agent is a tridecafluorooctyltriethoxysilane solution with a mass fraction of 8-12%. The mixing process after adding the coupling agent is carried out under ultrasonic conditions with an ultrasonic power of 500-600 W and a time of 30-40 min.

7. The preparation method according to claim 5, characterized in that, The mass ratio of the SiO2 aerogel particles to the polyimide nanofibers is 7:3-9:1; the polyimide nanofibers have a diameter of 200-300 nm, a length of 50-100 μm, and a tensile strength ≥800 MPa. They are prepared by electrospinning with the following parameters: voltage 25-30 kV, flow rate 0.5-1 mL / h, receiving distance 15-20 cm, and imidization at 300℃ for 2 h after spinning.

8. The preparation method according to claim 5, characterized in that, Before crosslinking and curing, the sample obtained from the degassing treatment needs to be subjected to low-temperature treatment. The low-temperature treatment is to pre-freeze at -50℃ to -60℃ for 12-15 hours, with a cooling rate of 5℃ / h. Crosslinking and curing is carried out by segmented thermal crosslinking at 60-80℃ and a vacuum degree of -0.08 to -0.09 MPa to achieve curing.

9. The preparation method according to claim 5, characterized in that, The segmented thermal crosslinking is carried out as follows: initial crosslinking is performed by holding at 60℃ for 8 hours, followed by deep crosslinking by holding at 70℃ for 12 hours, and finally, it is performed by holding at 80℃ for 4-10 hours, with a total curing time of 24-30 hours.

10. The application of an aerogel composite insulation material according to any one of claims 1-4 or an aerogel composite insulation material prepared by any one of claims 5-9 in LNG ships.

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