Composite nanoporous aerogel thermal insulation material

Abstract

The application specifically discloses a composite nanopore aerogel heat insulation material, which comprises a heat insulation layer, an adhesive layer and a waterproof layer arranged in sequence, wherein the heat insulation layer is composed of aerogel core-shell particles and polyimide oligomers, the main component of the adhesive layer is polyurethane flame-retardant glue; the aerogel core-shell particles take nanometer SiO2 aerogel as a core, and a shell layer is formed by polyamide acid solution and an amino-terminated hyperbranched polysiloxane crosslinking agent, and has a double-pore structure. The aerogel core-shell particles can be fully dispersed in the polyimide oligomers to form a heat insulation layer with rich internal pore structure and large specific surface area. The heat insulation layer, together with the polyurethane flame-retardant glue and the aluminum foil waterproof layer, can effectively play a role in high heat insulation, excellent mechanical properties and condensation prevention, and has good comprehensive performance in the field of special-shaped pipeline heat insulation.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of thermal insulation materials, and more particularly to a composite nanopore aerogel thermal insulation material. BACKGROUND

[0002] Thermal insulation materials refer to materials capable of blocking heat flow transmission, including superfine glass wool and flame-retardant closed-cell rubber plastic thermal insulation materials. At present, the flame-retardant closed-cell rubber plastic thermal insulation material is widely used in the industry, and the reason is that the flame-retardant closed-cell rubber plastic thermal insulation material has a small thermal conductivity, a light volume weight, a closed-cell surface with anti-condensation function, good toughness, and can be directly coated on the surface of an object through the adhesion of an adhesive, and the construction is efficient. However, the flame-retardant closed-cell rubber plastic thermal insulation material is prone to aging, causing cracking or hardening and other physical property degradation phenomena, and the thermal insulation performance will sharply decrease. Meanwhile, it is a flammable product, and after adding a flame retardant, it will still burn as long as it is not away from the fire source. In addition to spreading flames to cause fires, it also produces molten droplets and toxic gases, and the smoke concentration does not meet the standard, which will seriously harm people's health.

[0003] As a new type of thermal insulation material, the aerogel felt gradually replaces the flame-retardant closed-cell rubber plastic thermal insulation material. The aerogel felt is prepared by dipping a fiber material in a sol of SiO2 aerogel in the early stage of preparation of the aerogel, forming a composite gel, and obtaining the aerogel thermal insulation felt through drying treatment. The aerogel felt has an ultra-low thermal conductivity, and the thermal conductivity thereof at room temperature is about 0.018-0.020 W / m·K. When the aerogel felt reaches the same thermal insulation effect as the flame-retardant closed-cell rubber plastic thermal insulation material or the superfine glass wool, the thickness thereof is only half of that of the flame-retardant closed-cell rubber plastic thermal insulation material or the superfine glass wool, and the thickness is relatively thin, and the aerogel felt is suitable for narrow spaces such as ships.

[0004] However, the aerogel felt is accompanied by a certain degree of dust release in the actual construction process, and the joint is difficult to handle, and the thermal bridge effect is easy to occur, which leads to the difficulty of the aerogel felt in being applied to the pipe coating of a relatively complex structure, such as the coating of a bent pipe. Meanwhile, the aerogel felt is hydrophobic as a whole, but allows water vapor to pass through, and therefore, the aerogel felt is not suitable for use in humid environments such as the seaside, and when used for a long time, water will accumulate in the aerogel felt, leading to thermal insulation failure. Therefore, the comprehensive use performance of the aerogel felt is not good, and it is difficult to meet the demand of actual use, and is greatly limited in the high-temperature thermal insulation field. SUMMARY

[0005] In order to solve the problem of poor comprehensive use performance of the aerogel felt, the application provides a composite nanopore aerogel thermal insulation material.

[0006] The application provides a composite nanopore aerogel thermal insulation material, and the following technical scheme is adopted:

[0007] The composite nanoporous aerogel thermal insulation material comprises a thermal insulation layer, an adhesive layer and a waterproof layer arranged in sequence, wherein the thermal insulation layer is composed of aerogel core-shell particles and polyimide oligomers, and the main component of the adhesive layer is polyurethane flame-retardant glue.

[0008] The aerogel core-shell particles are prepared by the following method: pre-ultrasonic dispersion of nano-SiO2 aerogel to obtain a homogeneous mixture; adding diamine and dianhydride according to a weight ratio of 1:(1.2-2.4), stirring and dispersing to obtain a polyamic acid solution; blending the polyamic acid solution, the homogeneous mixture and an amino-terminated hyperbranched polysiloxane crosslinking agent, wherein the weight ratio of the nano-SiO2 aerogel particles, the diamine and the amino-terminated hyperbranched polysiloxane crosslinking agent is 1:(0.05-0.15):(0.0175-0.0526), microwave irradiation synthesis, and drying to obtain the aerogel core-shell particles.

[0009] The thermal insulation layer is prepared by the following method: mixing the aerogel core-shell particles, aliphatic alkyl diamine and dianhydride according to a weight ratio of 1:(2-3):(3-4.5), adding an amino-terminated hyperbranched polysiloxane crosslinking agent, mixing uniformly, and then pouring into a film device, drying after gelation to obtain the thermal insulation layer.

[0010] Further, in the preparation step of the aerogel core-shell particles, the microwave irradiation power is 600-700W, and the microwave irradiation time is 20-30min.

[0011] Further, in the preparation step of the aerogel core-shell particles, the size of the amino-terminated hyperbranched polysiloxane crosslinking agent is 0.5-50μm.

[0012] Further, in the preparation step of the thermal insulation layer, the weight ratio of the aerogel core-shell particles, the aliphatic alkyl diamine and the dianhydride is 1:2.5:3.75.

[0013] Further, in the preparation step of the thermal insulation layer, the weight ratio of the amino-terminated hyperbranched polysiloxane crosslinking agent to the aliphatic alkyl diamine is 0.35:1.

[0014] Further, in the preparation step of the thermal insulation layer, the number of alkyl carbon chains in the aliphatic alkyl diamine is 6-8.

[0015] Further, in the composite nanoporous aerogel thermal insulation material, the thickness ratio of the thermal insulation layer to the adhesive layer is 1:(0.00005-0.0001).

[0016] Further, the waterproof layer is a waterproof aluminum foil.

[0017] By adopting the technical scheme, the application has at least the following advantages:

[0018] Firstly, in the application, the nano-SiO2 aerogel particles are used as the core, the diamine and the dianhydride are polymerized under the action of the crosslinking agent, the amino-terminated hyperbranched polysiloxane, and a microwave synthesis method is used to form a shell layer with a moderate thickness and a multi-nanopore structure on the surface of the nano-SiO2 aerogel particles; the amino group of the amino-terminated hyperbranched polysiloxane can react with the anhydride end amino group of the polyamic acid oligomer to form an imide bond, thereby forming a stable organic-inorganic hybrid gel network on the surface of the nano-SiO2 aerogel particles; compared with the nano-SiO2 aerogel particles, the aerogel core-shell particles have a larger specific surface area and a more abundant nanopore structure, which can effectively improve the heat insulation effect of the heat insulation layer.

[0019] Secondly, the aerogel core-shell particles have an imide bond on the surface, and the aerogel core-shell particles have excellent compatibility in the polyimide oligomer and can be fully dispersed in the polyimide oligomer without stress concentration points; in addition, the diamine in the polyimide oligomer contains a flexible ether bond long chain, which improves the Young's modulus of the whole heat insulation layer and exhibits more excellent toughness; at the same time, the aerogel core-shell particles, the diamine, and the dianhydride are crosslinked under the action of the crosslinking agent, the amino-terminated hyperbranched polysiloxane macromonomer, to form a heat insulation layer with an abundant internal pore structure; the heat insulation layer has an extremely low thermal conductivity and good heat insulation effect.

[0020] Thirdly, the polyurethane flame-retardant adhesive is a thermoplastic adhesive, and the polyurethane flame-retardant adhesive contains an isocyanate group, which can react with the unreacted amino group on the surface of the heat insulation layer to increase the connection strength between the adhesive layer and the heat insulation layer, convert the hydrophilic amino group into a hydrophobic carbamate group, and reduce the moisture absorption at the interface between the adhesive layer and the heat insulation layer; at the same time, the waterproof layer further reduces the moisture absorption of the heat insulation material, reduces the penetration of water vapor, and the waterproof layer and the adhesive layer work together to enable the heat insulation layer to maintain long-term heat insulation performance and excellent mechanical properties.

[0021] Secondly, in the application, the raw material ratio and the microwave process parameters in the step of preparing the aerogel core-shell particles are optimized, so that the thickness of the aerogel core-shell particles is moderate and the specific surface area is maximized, which can effectively reduce the transfer of heat and thus play an excellent heat insulation role.

[0022] Thirdly, in the application, the preparation parameters of the heat insulation layer are optimized, so that the heat insulation layer can have excellent heat insulation performance and mechanical properties, thereby being able to flexibly and tightly cover the pipe with a special-shaped structure and expand the use range of the heat insulation material. DETAILED DESCRIPTION

[0023] The application is further illustrated by the following examples, comparative examples, and test results.

[0024] Preparation example of the crosslinking agent

[0025] An amino-terminated hyperbranched polysiloxane crosslinking agent is prepared according to the following steps:

[0026] 1 kg of solvent tetrahydrofuran is added into a reaction kettle, and 100 g of γ-aminopropylmethyldiethoxysilane, 660 g of tetraethoxysilane, and 50 g of phenyltrimethoxysilane are added into the tetrahydrofuran, which are stirred and mixed to obtain a reaction mixture;

[0027] After the reaction mixture is cooled to 0°C in an ice bath, 350 g of deionized water is added dropwise through a syringe, and stirred vigorously for 1 h, and then the temperature is kept at 0°C for 1 h, and then the temperature is increased to 50°C for 2 h, and then the reaction mixture is transferred to a rotary evaporator for rotary evaporation under reduced pressure, and the rotary evaporation temperature is controlled at 55°C, and then a white powder product is obtained by rotary evaporation, which is the amino-terminated hyperbranched polysiloxane crosslinking agent;

[0028] The amino-terminated hyperbranched polysiloxane crosslinking agent is ground in a grinder, and sieved according to the size, to obtain the amino-terminated hyperbranched polysiloxane crosslinking agent with a size of 1-500 nm, 0.5-50 μm, and 50-100 μm.

[0029] Example

[0030] Example 1

[0031] A composite nanoporous aerogel thermal insulation material, which has a structure of a thermal insulation layer, an adhesive layer, and a waterproof layer arranged in sequence; and is prepared according to the following steps:

[0032] Aerogel core-shell particle preparation:

[0033] 1 kg of nano-SiO2 aerogel particles are weighed and placed in anhydrous ethanol for ultrasonic dispersion, 50 g of a dispersant polyvinylpyrrolidone and 200 g of deionized water are added into the anhydrous ethanol, and the mixture is uniformly mixed and then ultrasonically oscillated to obtain a homogeneous mixture;

[0034] Under a nitrogen atmosphere, 100 g of 2,3-dimethylbenzotriazole and 200 mL of N-methylpyrrolidone, and 150 g of 3,3',4,4'-biphenyl tetracarboxylic dianhydride are added into the homogeneous mixture, and stirred for 3 h, and a polyamic acid solution is obtained after the reaction is sufficiently completed;

[0035] The homogeneous mixture, the polyamic acid solution, and 35 g of the amino-terminated hyperbranched polysiloxane crosslinking agent (with a size of 0.5-50 μm) are stirred and blended, and subjected to microwave irradiation heating, the microwave power is 600 W, the microwave heating time is 30 min, and after the microwave heating is completed, the mixture is placed at 70°C for vacuum drying for 12 h to obtain the aerogel core-shell particles;

[0036] Thermal insulation layer preparation:

[0037] The aerogel core-shell particles, 1,6-hexanediamine, 3,3',4,4'-biphenyl tetracarboxylic dianhydride are mixed according to the weight ratio of 1:2.5:3.75, and an amino-terminated hyperbranched polysiloxane crosslinking agent (with a size of 1 nm-100 μm) is added, the weight ratio of the crosslinking agent to 1,6-hexanediamine is 0.35:1, after stirring and mixing uniformly, pouring into a mold, the thickness of the mold is 20 mm, and the gelation is carried out, after the gelation is completed, aging for 24 h to ensure complete gelation, removing the mold, and vacuum drying at 70°C for 12 h to obtain the thermal insulation layer;

[0038] Multi-layer structure composite:

[0039] The polyurethane flame-retardant glue is coated on the surface of the thermal insulation layer, the coating thickness of the polyurethane flame-retardant glue is 10 μm, the waterproof aluminum foil film is pressed on the polyurethane flame-retardant glue, and the polyurethane flame-retardant glue is cured, and the composite nanoporous aerogel thermal insulation material is obtained after curing.

[0040] The model of the polyurethane flame-retardant glue is CoolTherm UR-389.

[0041] Example 2-3

[0042] A composite nanoporous aerogel thermal insulation material, which is different from example 1 in that the parameters in the preparation step of the aerogel core-shell particles are different, and more specifically, the weight ratio of the nano-SiO2 aerogel particles, 2,3-dimethyl benzotriazole and the amino-terminated hyperbranched polysiloxane crosslinking agent is different, and more specifically as follows:

[0043] The weight ratio of the nano-SiO2 aerogel particles, 2,3-dimethyl benzotriazole and the amino-terminated hyperbranched polysiloxane crosslinking agent in example 2 is 1:0.05:0.0175;

[0044] The weight ratio of the nano-SiO2 aerogel particles, 2,3-dimethyl benzotriazole and the amino-terminated hyperbranched polysiloxane crosslinking agent in example 3 is 1:0.15:0.0526.

[0045] Example 4-5

[0046] A composite nanoporous aerogel thermal insulation material, which is different from example 1 in that the parameters in the preparation step of the aerogel core-shell particles are different, and more specifically, the weight ratio of 2,3-dimethyl benzotriazole to 3,3',4,4'-biphenyl tetracarboxylic dianhydride is different, and more specifically as follows:

[0047] In example 4, the weight ratio of 2,3-dimethyl benzotriazole to 3,3',4,4'-biphenyl tetracarboxylic dianhydride is 1:1.2;

[0048] In Example 5, the weight ratio of 2,3-dimethylbenzotriazole to 3,3',4,4'-biphenyltetracarboxylic dianhydride is 1:2.4.

[0049] Examples 6-8

[0050] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the parameters in the preparation step of the aerogel core-shell particles are different, specifically the microwave irradiation parameters are different, more specifically as follows:

[0051] In Example 6, the microwave irradiation power is 700 W, and the microwave irradiation time is 20 min;

[0052] In Example 7, the microwave irradiation power is 800 W, and the microwave irradiation time is 15 min;

[0053] In Example 8, the microwave irradiation power is 400 W, and the microwave irradiation time is 60 min.

[0054] Examples 9-10

[0055] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the parameters in the preparation step of the aerogel core-shell particles are different, specifically the size of the crosslinking agent is different, more specifically as follows:

[0056] In Example 9, the size of the crosslinking agent is 1-500 nm;

[0057] In Example 10, the size of the crosslinking agent is 50-100 μm.

[0058] Examples 11-12

[0059] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the parameters in the preparation step of the thermal insulation layer are different, specifically the weight ratio of the aerogel core-shell particles, aliphatic alkyl diamine, and dianhydride is different, more specifically as follows:

[0060] In Example 11, the weight ratio of the aerogel core-shell particles, 1,6-hexanediamine, and 3,3',4,4'-biphenyltetracarboxylic dianhydride is 1:2:3;

[0061] In Example 12, the weight ratio of the aerogel core-shell particles, 1,6-hexanediamine, and 3,3',4,4'-biphenyltetracarboxylic dianhydride is 1:3:4.5.

[0062] Examples 13-14

[0063] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the parameters in the preparation step of the thermal insulation layer are different, specifically the weight ratio of the amino-terminated hyperbranched polysiloxane crosslinking agent and aliphatic alkyl diamine is different, more specifically as follows:

[0064] The weight ratio of the amino-terminated hyperbranched polysiloxane crosslinking agent to 1,6-hexanediamine in Example 13 is 0.3:1;

[0065] The weight ratio of the amino-terminated hyperbranched polysiloxane crosslinking agent to 1,6-hexanediamine in Example 14 is 0.4:1.

[0066] Examples 15-17

[0067] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the parameters in the preparation step of the thermal insulation layer are different, specifically, the number of alkyl carbon chains in the aliphatic alkyl diamine is different, and more specifically as follows:

[0068] 1,8-octanediamine is used instead of 1,6-hexanediamine in Example 15;

[0069] 1,4-butanediamine is used instead of 1,6-hexanediamine in Example 16;

[0070] 1,10-decanediamine is used instead of 1,6-hexanediamine in Example 17.

[0071] Examples 18-20

[0072] A composite nanoporous aerogel thermal insulation material, which differs from Example 1 in that the thickness ratio of the thermal insulation layer and the adhesive layer is different, and more specifically as follows:

[0073] The thickness of the thermal insulation layer is 20 mm and the thickness of the adhesive layer is 20 μm in Example 18;

[0074] The thickness of the thermal insulation layer is 20 mm and the thickness of the adhesive layer is 2 μm in Example 19;

[0075] The thickness of the thermal insulation layer is 20 mm and the thickness of the adhesive layer is 50 μm in Example 20.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] A thermal insulation material, which has a structure in which a thermal insulation layer, an adhesive layer, and a waterproof layer are sequentially stacked; and is prepared according to the following steps:

[0079] is prepared according to the following steps:

[0080] Preparation of the thermal insulation layer:

[0081] The nano-SiO2 aerogel particles are ultrasonically dispersed in anhydrous ethanol, a dispersant polyvinylpyrrolidone and deionized water are added to the anhydrous ethanol, and the mixture is uniformly mixed and then ultrasonically oscillated to obtain a homogeneous mixture;

[0082] The nano-SiO2 aerogel particles, 1,6-hexanediamine, 3,3',4,4'-biphenyl tetracarboxylic dianhydride are mixed according to the weight ratio of 1:2.5:3.75, and an amino-terminated hyperbranched polysiloxane crosslinking agent is added, the weight ratio of the crosslinking agent to 1,6-hexanediamine is 0.35:1, after stirring and mixing, pour into the mold, the mold thickness is 20mm, gelation is carried out, after gelation is completed, aging for 24h to ensure complete gelation, remove the mold, and place it in a vacuum drying oven at 70°C for 12h to obtain a thermal insulation layer;

[0083] Multi-layer structure composite:

[0084] A polyurethane flame-retardant adhesive is coated on the surface of the thermal insulation layer, the coating thickness of the polyurethane flame-retardant adhesive is 10μm, a waterproof aluminum foil film is pressed on the polyurethane flame-retardant adhesive, and the polyurethane flame-retardant adhesive is allowed to cure, and a composite nanoporous aerogel thermal insulation material is obtained after curing is completed.

[0085] The model of the polyurethane flame-retardant adhesive is CoolTherm UR-389.

[0086] Comparative Example 2

[0087] A kind of thermal insulation material, the difference between Example 1 is that the core-shell aerogel particle preparation step and the selection of crosslinking agent in the preparation step of thermal insulation layer are different, as follows: using amino-terminated trihydroxymethylpropane trimer propylene glycol ether instead of amino-terminated hyperbranched polysiloxane crosslinking agent.

[0088] Comparative Example 3

[0089] A kind of thermal insulation material, the difference between Example 1 is that the structure of thermal insulation material is different, the waterproof layer is missing in this comparative example, and the polyurethane flame-retardant adhesive is coated on the surface of the thermal insulation layer and then directly cured, the coating thickness of the polyurethane flame-retardant adhesive is 10μm.

[0090] Comparative Example 4

[0091] A kind of thermal insulation material, the difference between Example 1 is that the structure of thermal insulation material is different, the adhesive layer is missing in this comparative example, and the specific operation is as follows:

[0092] Aerogel core-shell particle preparation:

[0093] 1kg of nano-SiO2 aerogel particles are weighed and placed in anhydrous ethanol for ultrasonic dispersion, 50g of dispersant polyvinylpyrrolidone and 200g of deionized water are added to the anhydrous ethanol, and the mixture is uniformly mixed and then ultrasonically oscillated to obtain a homogeneous mixture;

[0094] Under the nitrogen atmosphere, 100 g of 2,3-dimethylbenzotriazole and 200 mL of N-methylpyrrolidone were added to the homogeneous mixture, 150 g of 3,3',4,4'-biphenyl tetracarboxylic dianhydride was stirred for 3 h, and a polyamic acid solution was obtained after the reaction was completed;

[0095] The homogeneous mixture, the polyamic acid solution, and 35 g of an amino-terminated hyperbranched polysiloxane crosslinking agent (with a size of 0.5-50 μm) were stirred and blended, microwave irradiation heating was performed, the microwave power was 600 W, the microwave heating time was 30 min, and after the microwave heating was completed, vacuum drying was performed at 70 °C for 12 h to obtain aerogel core-shell particles;

[0096] Double-layer composite:

[0097] The aerogel core-shell particles, 1,6-hexanediamine, and 3,3',4,4'-biphenyl tetracarboxylic dianhydride were mixed according to a weight ratio of 1:2.5:3.75, an amino-terminated hyperbranched polysiloxane crosslinking agent (with a size of 1 nm-100 μm) was added, the weight ratio of the crosslinking agent to 1,6-hexanediamine was 0.35:1, stirring was performed until uniform, then the mixture was poured into a mold, a waterproof aluminum foil was laid at the bottom of the mold, the thickness of the mold was 20 mm, gelation was performed, after the gelation was completed, aging was performed at 70 °C for 24 h to ensure complete gelation, the mold was removed, and vacuum drying was performed at 70 °C for 12 h to obtain a thermal insulation material.

[0098] Comparative Example 5

[0099] A thermal insulation material, which differed from Example 1 in that an EVA flame-retardant adhesive with the same thickness was used instead of the polyurethane flame-retardant adhesive, and the grade of the EVA flame-retardant adhesive was EA100-B.

[0100] Detection data

[0101] 1. Thermal conductivity detection: The thermal conductivity of Examples 1-20 and Comparative Examples 1-5 was detected according to the detection method described in GB / T 10295;

[0102] 2. Condensation test: The thermal conductivity of Examples 1-20 and Comparative Examples 1-5 after the condensation test was re-detected according to the detection method described in the “Condensation Test Method for Air Conditioning and Ventilation Pipeline Thermal Insulation Materials”.

[0103] 3. Tensile strength and elongation at break: The tensile property testing equipment was a universal material testing machine with a model number of 5567, and the tensile property of the thermal insulation material was tested. The test parameters were as follows: the total length of the sample was 75 mm, the gauge length was 10 mm, the pre-load was 1 N, and the loading rate was 10 mm / min.

[0104] Table 1. Performance detection data of Examples 1-20 and Comparative Examples 1-5

[0105]

[0106] Conclusion

[0107] The difference between the thermal conductivity after the condensation test and the initial thermal conductivity indirectly reflects the hygroscopicity of the thermal insulation material. The lower the difference, the lower the hygroscopicity, and the longer the thermal insulation effect in a humid environment.

[0108] Furthermore, the applicant repeatedly bends Examples 1-20, and no dust appears during the bending process.

[0109] According to the above test data, it can be seen that:

[0110] First, the only difference between Example 1 and Comparative Example 1 is that the nano-SiO2 aerogel particles in Comparative Example 1 are not made into a core-shell structure, but are directly reacted with aliphatic alkyl diamine and dianhydride. The nano-SiO2 aerogel particles are difficult to fully disperse in the polyimide oligomer, and are prone to form an aggregated state, resulting in a local thermal short circuit, which increases the thermal conductivity of the thermal insulation material and reduces the thermal insulation performance. Moreover, the nano-SiO2 aerogel particles in the aggregated state cause stress concentration points in the thermal insulation material, reducing the mechanical properties of the thermal insulation material. At the same time, the pore structure of the nano-SiO2 aerogel particles cannot be fully preserved, and the aliphatic alkyl diamine and dianhydride infiltrate and block the pores of the nano-SiO2 aerogel particles, preventing the nano-SiO2 aerogel particles from forming a complete thermal resistance network structure in the composite film, further reducing the thermal insulation performance of the thermal insulation material.

[0111] Second, the only difference between Example 1 and Comparative Example 2 is the selection and weight ratio of the crosslinking agent. In Comparative Example 2, the crosslinking agent is a traditional amino-terminated crosslinking agent. For the aerogel core-shell particles, the polyamide acid oligomer can coat the surface of the nano-SiO2 aerogel particles, but the porosity of the shell structure formed by the polyamide acid oligomer is significantly reduced through only microwave synthesis. Similarly, during the preparation of the thermal insulation layer, the formation of the thermal resistance network structure of the thermal insulation layer is hindered, which seriously affects the thermal insulation performance of the thermal insulation layer.

[0112] Third, the only difference between Example 1 and Comparative Examples 3-4 is the structure of the thermal insulation material. Comparative Example 3 lacks a water-blocking layer, and the thermal insulation performance of Comparative Example 3 is reduced. The reason is that the thermal insulation layer in Comparative Example 3 contains hydrophilic groups such as amino and carboxyl groups, which easily lead to the intrusion of moisture in the air, and the porous structure of the thermal insulation layer is prone to collapse due to moisture absorption and expansion, weakening the heat flow blocking effect of the thermal insulation layer, and leading to a decrease in the overall thermal insulation performance of the thermal insulation material.

[0113] In Comparative Example 4, the adhesive layer is absent, and the waterproof layer is placed in the mold first. While the thermal insulation layer is reacting, the amino groups and carboxyl groups of the thermal insulation layer can interact with the hydroxyl groups on the surface of the aluminum foil layer through hydrogen bonds to make the aluminum foil layer adhere to the surface of the thermal insulation layer, and the aluminum foil layer and the thermal insulation layer are simultaneously formed. However, through actual testing, the connection strength between the aluminum foil layer and the thermal insulation layer in Comparative Example 4 is weak, and interface separation easily occurs, which causes the waterproof layer to lose the moisture-proof effect on the thermal insulation layer, and the thermal insulation layer material easily absorbs moisture and swells, resulting in poor thermal insulation effect.

[0114] Fourth, the difference between Example 1 and Comparative Example 5 is that the adhesives used in the adhesive layer are different. The adhesive used in Comparative Example 5 is EVA flame-retardant adhesive. Compared with polyurethane flame-retardant adhesive, the cross-linking strength between EVA adhesive and the thermal insulation layer is low, the reactivity of carboxyl groups in EVA with amino groups is low, it is difficult to form cross-linking between the interface of the adhesive layer and the thermal insulation layer, and the adhesive layer is prone to separate from the thermal insulation layer. Moreover, the EVA flame-retardant adhesive contains hydrophilic groups such as carboxyl groups, and the hydrophobic effect is not good, which still easily allows water to invade, causing the gel pore structure at the interface to swell due to moisture absorption, weakening the heat flow transmission resistance of the surface layer of the thermal insulation layer, and resulting in a decrease in the overall thermal insulation performance of the thermal insulation material. Therefore, the use of polyurethane flame-retardant adhesive in the present application can significantly improve the overall thermal insulation performance and mechanical properties of the thermal insulation material.

[0115] Fifth, in Examples 1-10, the preparation parameters of the aerogel core-shell particles are different, and the structures of the prepared aerogel core-shell particles are different, which have a great influence on the thermal insulation performance of the thermal insulation material. The thermal insulation performance is not improved when the shell layer is too thick or too thin. When the weight ratio of the shell layer material increases, the shell layer is thicker, which helps to improve the mechanical properties of the thermal insulation material, but the overall specific surface area of the aerogel core-shell particles decreases, which is not conducive to the improvement of the thermal insulation performance. When the weight ratio of the shell layer material decreases, the shell layer is thinner, which helps to improve the thermal insulation performance of the thermal insulation material, but the compatibility of the aerogel core-shell particles and the polyimide oligomer decreases, which is not conducive to the improvement of the mechanical properties.

[0116] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0117] In addition, the above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be construed as limiting the scope of the patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A composite nanoporous aerogel thermal insulation material, characterized in that, The composite type nano-porous aerogel thermal insulation material comprises a thermal insulation layer, an adhesive layer and a waterproof layer arranged in sequence, wherein the thermal insulation layer is composed of aerogel core-shell particles and polyimide oligomers, and the main component of the adhesive layer is polyurethane flame-retardant glue. The aerogel core-shell particles are prepared by the following method: uniformly dispersing nano-SiO2 aerogel by ultrasonic dispersion to obtain a homogeneous mixture; adding diamine and diacid anhydride in a weight ratio of 1:(1.2-2.4), stirring and dispersing to obtain a polyamide acid solution; blending the polyamide acid solution, the homogeneous mixture and an amino-terminated hyperbranched polysiloxane crosslinking agent, wherein the weight ratio of the nano-SiO2 aerogel particles, the diamine and the amino-terminated hyperbranched polysiloxane crosslinking agent is 1:(0.05-0.15):(0.0175-0.0526), and performing microwave irradiation synthesis at a microwave irradiation power of 600-700 W for 20-30 min; and drying to obtain the aerogel core-shell particles. The thermal insulation layer is prepared by the following method: mixing the aerogel core-shell particles, aliphatic alkyl diamine and diacid anhydride in a weight ratio of 1:(2-3):(3-4.5), adding the amino-terminated hyperbranched polysiloxane crosslinking agent, uniformly mixing, and then pouring into a mold, drying after gelation to obtain the thermal insulation layer.

2. The composite nanoporous aerogel thermal insulation material of claim 1, wherein: In the preparation step of the aerogel core-shell particles, the size of the amino-terminated hyperbranched polysiloxane crosslinking agent is 0.5-50 μm.

3. The composite nanoporous aerogel thermal insulation material as described in claim 1, characterized in that: In the preparation step of the thermal insulation layer, the weight ratio of the aerogel core-shell particles, the aliphatic alkyl diamine and the diacid anhydride is 1:2.5:3.

75.

4. The composite nanoporous aerogel thermal insulation material of claim 3, wherein: In the preparation step of the thermal insulation layer, the weight ratio of the amino-terminated hyperbranched polysiloxane crosslinking agent to the aliphatic alkyl diamine is 0.35:

1.

5. The composite nanoporous aerogel thermal insulation material of claim 4, wherein: In the preparation step of the thermal insulation layer, the number of alkyl carbon chains in the aliphatic alkyl diamine is 6-8.

6. The composite nanoporous aerogel thermal insulation material of claim 1, wherein: In the composite type nano-porous aerogel thermal insulation material, the thickness ratio of the thermal insulation layer to the adhesive layer is 1:(0.00005-0.0001).

7. The composite nanoporous aerogel thermal insulation material of claim 1, wherein: the aerogel has a density of 0.1 g / cm3 or less. The waterproof layer is a waterproof aluminum foil.

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