Thermal insulation composite material and preparation method thereof

Abstract

The invention relates to a thermal insulation composite material and a preparation method thereof. The preparation method comprises the following steps: (1) preparing thermoplastic polyurethane; (2) carrying out graft modification on the thermoplastic polyurethane; (3) pretreating the hollow glass microspheres; (4) preparing dispersion liquid; and (5) coating the dispersion liquid. Compared with the prior art, more active groups are introduced through synthesis and graft modification of the thermoplastic polyurethane, the binding force between the thermoplastic polyurethane and the hollow glass microspheres is enhanced, and the overall performance of the composite material is improved. The hollow glass microspheres are pretreated, so that the surface performance of the hollow glass microspheres is improved, and the compatibility and the bonding strength of the hollow glass microspheres and the modified thermoplastic polyurethane are further improved.

Description

Technical Field

[0001] The present invention relates to the technology of thermal insulation composite materials, and particularly to a thermal insulation composite material and a preparation method thereof. Background Art

[0002] In the current fields of ocean resource development and energy storage, as an important device, the underwater oil storage bladder faces many challenging operating environments. With the rapid development of the ocean economy, the demands for the storage of crude oil, refined oil, the development of offshore (marginal) oilfields, and the long-term storage and replenishment of fuels on islands are increasing day by day, and the performance requirements for underwater oil storage bladder materials are also getting higher and higher.

[0003] The underwater environment has large temperature variations, and the storage and transportation of oil substances have certain requirements for temperature. In a low-temperature environment, wax separation occurs in crude oil and heating is required. Therefore, the underwater oil storage bladder material needs to have good thermal insulation performance to maintain the oil substances within an appropriate temperature range and reduce the impact of temperature changes on the properties of the oil substances. However, the existing oil storage bladder materials often fall short in terms of thermal insulation performance and are difficult to maintain a stable thermal insulation effect over a wide temperature range. In addition, considering the installation and use convenience of the underwater oil storage bladder, the material should also have a certain degree of flexibility to adapt to different installation environments and shape requirements.

[0004] In the existing technology, the research on underwater oil storage bladder materials mainly focuses on the improvement of single performance, such as improving the oil resistance or thermal insulation performance of the material, but there are few studies that can comprehensively consider the synergistic optimization of multiple performances. Some studies have tried to improve the material performance by adding different fillers or adopting different preparation processes, but the effects are not ideal. Although some materials have improved in one aspect of performance, they have sacrificed other performances, such as improving the oil resistance but reducing the thermal insulation performance, or enhancing the rigidity but losing the flexibility.

[0005] Therefore, it is of great practical significance and broad application prospects to develop a composite material and a preparation method thereof that can comprehensively meet various performance requirements such as oil resistance, seawater resistance, thermal insulation, and flexibility and are applicable to underwater oil storage bladders. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned existing technology and provide a thermal insulation composite material and a preparation method thereof, so as to improve the thermal insulation performance and flexibility of the thermal insulation composite material.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] A preparation method of a thermal insulation composite material includes the following steps:

[0009] (1) Preparation of thermoplastic polyurethane: Using 4,4'-diphenylmethane diisocyanate and polyether diol as raw materials, and dibutyltin dilaurate as a catalyst, a polyurethane prepolymer is obtained; 1,4-butanediol as a chain extender is added to the polyurethane prepolymer to obtain thermoplastic polyurethane;

[0010] (2) Graft modification of the thermoplastic polyurethane: The thermoplastic polyurethane is added to an N,N-dimethylformamide solution of glycidyl methacrylate, such that glycidyl methacrylate monomers are connected to the molecular chain of the thermoplastic polyurethane to obtain a first mixed solution; Glycidyl methacrylate and initiator azobisisobutyronitrile are added to the first mixed solution, and the glycidyl methacrylate graft monomers form branches through double bond reactions to obtain a second mixed solution; The second mixed solution is precipitated and filtered, and the precipitate is washed and dried to obtain the graft-modified thermoplastic polyurethane;

[0011] (3) Pretreatment of hollow glass microspheres: Remove impurities and oxides on the surface of the hollow glass microspheres, and soak the hollow glass microspheres in an ethanol solution containing silane coupling agent KH560 for a certain period of time, so that a silane coupling agent coating layer is formed on the surface of the hollow glass microspheres to obtain the pretreated hollow glass microspheres;

[0012] (4) Preparation of a dispersion: The graft-modified thermoplastic polyurethane, the pretreated hollow glass microspheres and N,N-dimethylformamide are stirred and mixed to obtain a dispersion. In the dispersion, according to mass parts, the components of each raw material are as follows: 20 - 60 parts of the graft-modified thermoplastic polyurethane, 30 - 180 parts of the N,N-dimethylformamide, and 5 - 15 parts of the hollow glass microspheres;

[0013] (5) Coating of the dispersion: The dispersion is coated on liquid crystal polymer fibers, and a thermal insulation composite material is obtained after drying.

[0014] In one embodiment, in the step (1), obtaining the polyurethane prepolymer includes the following steps:

[0015] Remove the moisture in the polyether diol, and heat the polyether diol to 50 - 60 °C;

[0016] Add 4,4'-diphenylmethane diisocyanate to the heated polyether diol, and the molar ratio of the 4,4'-diphenylmethane diisocyanate to the polyether diol is 2.2 - 2.5:1;

[0017] Add dibutyltin dilaurate as a catalyst to polyether diol and 4,4'-diphenylmethane diisocyanate. Under nitrogen protection, stir and react for 2 - 3 h to fully react the isocyanate groups of 4,4'-diphenylmethane diisocyanate with the hydroxyl groups of polyether diol to form a polyurethane prepolymer.

[0018] In one of the embodiments, in removing the moisture in the polyether diol, the following specific steps are included:

[0019] Heat the polyether diol to 100 - 120 °C and dehydrate it under vacuum for 2 - 3 h.

[0020] In one of the embodiments, in step (1), the reaction temperature of the chain extender 1,4-butanediol and the polyurethane prepolymer is 70 - 80 °C, the reaction time is 1 - 2 h, and the molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer is 0.9 - 1.1:1.

[0021] In one of the embodiments, before step (2), the following specific steps are further included:

[0022] Perform plasma treatment on the thermoplastic polyurethane. The power of the plasma treatment is 50 - 200 W, and the treatment time is 4 - 6 min.

[0023] In one of the embodiments, in step (2), when adding the thermoplastic polyurethane to the N,N-dimethylformamide solution of glycidyl methacrylate, the mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15 - 1:20, the reaction temperature is 50 - 60 °C, and the reaction time is 6 - 10 h.

[0024] In one of the embodiments, in step (2), when adding glycidyl methacrylate and the initiator azobisisobutyronitrile to the first mixture, the mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15 - 1:20, and the dosage of the initiator is 0.5 - 1% of the total mass of glycidyl methacrylate added twice.

[0025] In one of the embodiments, in step (2), the vacuum drying temperature of the thermoplastic polyurethane is 60 - 80 °C, and the vacuum drying time is 12 - 24 h.

[0026] In one of the embodiments, in step (3), the following specific steps are included:

[0027] Soak the hollow glass microspheres in a dilute hydrochloric acid solution to remove the surface impurities and oxides. The mass fraction of the dilute hydrochloric acid solution is 3 - 5%, and the soaking time is 1 - 2 h;

[0028] The hollow glass microspheres are repeatedly rinsed with deionized water until the rinsing solution becomes neutral, and after filtration, the hollow glass microspheres are dried at 80 - 100 °C for 3 - 5 h;

[0029] The dried hollow glass microspheres are immersed in an ethanol solution containing silane coupling agent KH560, wherein the mass fraction of the silane coupling agent in the ethanol solution of silane coupling agent KH560 is 2 - 4%, so as to form a coating layer of silane coupling agent on the surface of the hollow glass microspheres, and the pretreated hollow glass microspheres are obtained.

[0030] A thermal insulation composite material is prepared by the following preparation method:

[0031] (1) Prepare thermoplastic polyurethane: Using 4,4'-diphenylmethane diisocyanate and polyether diol as raw materials, and dibutyltin dilaurate as a catalyst to obtain a polyurethane prepolymer; adding chain extender 1,4-butanediol to the polyurethane prepolymer to obtain thermoplastic polyurethane;

[0032] (2) Graft-modify the thermoplastic polyurethane: Add the thermoplastic polyurethane to the N,N-dimethylformamide solution of glycidyl methacrylate, so that the glycidyl methacrylate monomer is connected to the molecular chain of the thermoplastic polyurethane to obtain a first mixed solution; add glycidyl methacrylate and initiator azobisisobutyronitrile to the first mixed solution, and make the glycidyl methacrylate graft monomer form branches through double bond reaction to obtain a second mixed solution; precipitate and filter the second mixed solution, wash and dry the precipitate to obtain the graft-modified thermoplastic polyurethane;

[0033] (3) Pretreat the hollow glass microspheres: Remove the impurities and oxides on the surface of the hollow glass microspheres, immerse the hollow glass microspheres in an ethanol solution containing silane coupling agent KH560 for a certain time, so as to form a coating layer of silane coupling agent on the surface of the hollow glass microspheres, and obtain the pretreated hollow glass microspheres;

[0034] (4) Prepare a dispersion: Stir and mix the graft-modified thermoplastic polyurethane, the pretreated hollow glass microspheres and N,N-dimethylformamide to obtain a dispersion. In the dispersion, according to mass parts, the components of each raw material are as follows: 20 - 60 parts of the graft-modified thermoplastic polyurethane, 30 - 180 parts of N,N-dimethylformamide and 5 - 15 parts of the hollow glass microspheres;

[0035] (5) Coating of the dispersion: Coat the dispersion on the liquid crystal polymer fiber, and obtain the thermal insulation composite material after drying.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] The present invention prepares a thermal insulation composite material by mixing hollow glass microspheres and thermoplastic polyurethane in a certain ratio. After being modified by hollow glass microspheres, thermoplastic polyurethane has good tensile properties at both low and high temperatures and also has a thermal insulation effect. Through testing, it is found that the thermal insulation ability of the modified thermoplastic polyurethane thermal insulation composite material of the present invention is significantly improved. By synthesizing and grafting and modifying thermoplastic polyurethane, more active groups are introduced, enhancing its binding force with hollow glass microspheres and improving the overall performance of the composite material. The hollow glass microspheres are pretreated to improve their surface properties, further enhancing their compatibility and binding strength with the modified thermoplastic polyurethane.

[0038] The thermal insulation composite material prepared by the present invention can be applied to underwater oil storage bags, such as crude oil, refined oil storage, offshore (marginal) oilfield development, long-term fuel storage and supply on islands, etc. It has excellent high and low temperature properties, and the applicable temperature range is at least -30 to 80 °C; and it has good thermal insulation performance, and the thermal conductivity can be as low as 0.05 W / (m·K). Specific Embodiments

[0039] The present invention will be described in detail below with reference to specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0040] A method for preparing a thermal insulation composite material includes the following steps:

[0041] (1) Prepare thermoplastic polyurethane: Using 4,4'-diphenylmethane diisocyanate and polyether diol as raw materials and dibutyltin dilaurate as a catalyst to obtain a polyurethane prepolymer; adding a chain extender 1,4-butanediol to the polyurethane prepolymer to obtain thermoplastic polyurethane;

[0042] (2) Graft and modify the thermoplastic polyurethane: Add the thermoplastic polyurethane to an N,N-dimethylformamide solution of glycidyl methacrylate so that glycidyl methacrylate monomers are connected to the molecular chain of the thermoplastic polyurethane to obtain a first mixed solution; add glycidyl methacrylate and an initiator azobisisobutyronitrile to the first mixed solution to make the glycidyl methacrylate graft monomers form branches through double bond reactions to obtain a second mixed solution; precipitate and filter the second mixed solution, wash and dry the precipitate to obtain the graft-modified thermoplastic polyurethane;

[0043] (3) Pretreat the hollow glass microspheres: Remove the impurities and oxides on the surface of the hollow glass microspheres, soak the hollow glass microspheres in an ethanol solution containing silane coupling agent KH560, so that a silane coupling agent coating layer is formed on the surface of the hollow glass microspheres, and obtain pretreated hollow glass microspheres;

[0044] (4) Prepare the dispersion: Stir and mix the graft-modified thermoplastic polyurethane, the pretreated hollow glass microspheres and N,N-dimethylformamide to obtain a dispersion. In the dispersion, according to mass parts, the components of each raw material are as follows: 20-60 parts of the graft-modified thermoplastic polyurethane, 30-180 parts of the N,N-dimethylformamide, and 5-15 parts of the hollow glass microspheres;

[0045] (5) Coating the dispersion: Coat the dispersion on the liquid crystal polymer fiber, and obtain the thermal insulation composite material after drying.

[0046] In the present invention, by mixing hollow glass microspheres and thermoplastic polyurethane in a certain ratio, a thermal insulation composite material is prepared. After the thermoplastic polyurethane is modified by the hollow glass microspheres, on the premise that its low-temperature and high-temperature tensile properties are good, it also has a thermal insulation effect. Through detection, it is found that the thermal insulation ability of the modified thermoplastic polyurethane thermal insulation composite material of the present invention is significantly improved. Through the synthesis and graft modification of thermoplastic polyurethane, more active groups are introduced, the binding force with the hollow glass microspheres is enhanced, and the overall performance of the composite material is improved. The hollow glass microspheres are pretreated to improve their surface properties, and further improve the compatibility and bonding strength with the modified thermoplastic polyurethane.

[0047] The thermal insulation composite material prepared by the present invention can be applied to underwater oil storage bags, such as crude oil, refined oil storage, offshore (marginal) oilfield development, long-term storage and supply of island fuels, etc. It has excellent high and low temperature properties, and the applicable temperature range is at least -30 to 80 °C; and it has good thermal insulation performance, and the thermal conductivity can be as low as 0.05 W / (m·K).

[0048] In one embodiment, in the step (1), obtaining the polyurethane prepolymer includes the following steps:

[0049] Remove the moisture in the polyether diol, and heat the polyether diol to 50-60 °C;

[0050] Add 4,4'-diphenylmethane diisocyanate to the heated polyether diol, and the molar ratio of the 4,4'-diphenylmethane diisocyanate to the polyether diol is 2.2-2.5:1;

[0051] Add dibutyltin dilaurate as a catalyst to polyether diol and 4,4'-diphenylmethane diisocyanate. Under nitrogen protection, stir and react for 2 - 3 h to fully react the isocyanate groups of 4,4'-diphenylmethane diisocyanate with the hydroxyl groups of polyether diol to form a polyurethane prepolymer.

[0052] In one of the embodiments, in removing the moisture in the polyether diol, the following specific steps are included:

[0053] Heat the polyether diol to 100 - 120 °C and dehydrate it under vacuum for 2 - 3 h.

[0054] In one of the embodiments, in step (1), the reaction temperature of the chain extender 1,4-butanediol and the polyurethane prepolymer is 70 - 80 °C, the reaction time is 1 - 2 h, and the molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer is 0.9 - 1.1:1.

[0055] In one of the embodiments, before step (2), the following specific steps are further included:

[0056] Perform plasma treatment on the thermoplastic polyurethane. The power of the plasma treatment is 50 - 200 W and the treatment time is 4 - 6 min.

[0057] In one of the embodiments, in step (2), when adding the thermoplastic polyurethane to the N,N-dimethylformamide solution of glycidyl methacrylate, the mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15 - 1:20, the reaction temperature is 50 - 60 °C, and the reaction time is 6 - 10 h.

[0058] In one of the embodiments, in step (2), when adding glycidyl methacrylate and the initiator azobisisobutyronitrile to the first mixture, the mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15 - 1:20, and the dosage of the initiator is 0.5 - 1% of the total mass of glycidyl methacrylate added twice.

[0059] In one of the embodiments, in step (2), the vacuum drying temperature of the thermoplastic polyurethane is 60 - 80 °C and the vacuum drying time is 12 - 24 h.

[0060] In one of the embodiments, in step (3), the following specific steps are included:

[0061] Soak the hollow glass microspheres in a dilute hydrochloric acid solution to remove the surface impurities and oxides. The mass fraction of the dilute hydrochloric acid solution is 3 - 5%, and the soaking time is 1 - 2 h;

[0062] The hollow glass microspheres are repeatedly rinsed with deionized water until the rinsing solution becomes neutral, and after filtration, the hollow glass microspheres are dried at 80 - 100 °C for 3 - 5 h;

[0063] The dried hollow glass microspheres are immersed in an ethanol solution containing silane coupling agent KH560 for a certain period of time. Among them, the mass fraction of the silane coupling agent in the ethanol solution of silane coupling agent KH560 is 2 - 4%, so that a layer of silane coupling agent coating layer is formed on the surface of the hollow glass microspheres, and the pretreated hollow glass microspheres are obtained.

[0064] In one embodiment, in the step (3), the dried hollow glass microspheres are immersed in an ethanol solution containing silane coupling agent KH560, and the immersion time is 3 - 5 h.

[0065] In one embodiment, in the step (3), after a layer of silane coupling agent coating layer is formed on the surface of the hollow glass microspheres, the hollow glass microspheres are taken out and dried at 80 - 100 °C for 3 - 5 h to obtain the pretreated hollow glass microspheres.

[0066] In one embodiment, in the step (5), the drying temperature is 80 - 120 °C and the drying time is 30 - 60 min.

[0067] A thermal insulation composite material is prepared by the following preparation method:

[0068] (1) Prepare thermoplastic polyurethane: Using 4,4'-diphenylmethane diisocyanate and polyether diol as raw materials and dibutyltin dilaurate as a catalyst to obtain a polyurethane prepolymer; adding chain extender 1,4-butanediol to the polyurethane prepolymer to obtain thermoplastic polyurethane;

[0069] (2) Graft-modify the thermoplastic polyurethane: Add the thermoplastic polyurethane to the N,N-dimethylformamide solution of glycidyl methacrylate so that the glycidyl methacrylate monomer is connected to the molecular chain of the thermoplastic polyurethane to obtain a first mixed solution; add glycidyl methacrylate and initiator azobisisobutyronitrile to the first mixed solution to make the glycidyl methacrylate graft monomer form branches through a double bond reaction to obtain a second mixed solution; precipitate and filter the second mixed solution, wash and dry the precipitate to obtain the graft-modified thermoplastic polyurethane;

[0070] (3) Pretreat the hollow glass microspheres: Remove the impurities and oxides on the surface of the hollow glass microspheres, immerse the hollow glass microspheres in an ethanol solution containing silane coupling agent KH560 for a certain period of time to form a layer of silane coupling agent coating layer on the surface of the hollow glass microspheres, and obtain the pretreated hollow glass microspheres;

[0071] (4) Preparation of dispersion liquid: The graft-modified thermoplastic polyurethane, pretreated hollow glass microspheres, and N,N-dimethylformamide are stirred and mixed to obtain a dispersion liquid. In the dispersion liquid, according to mass parts, the components of each raw material are as follows: 20-60 parts of the graft-modified thermoplastic polyurethane, 30-180 parts of the N,N-dimethylformamide, and 5-15 parts of the hollow glass microspheres;

[0072] (5) Coating of dispersion liquid: The dispersion liquid is coated on the liquid crystal polymer fiber, and a thermal insulation composite material is obtained after drying.

[0073] The preparation method of the modified polyurethane-based thermal insulation composite material of the present invention will be described below with reference to examples.

[0074] The information of the raw materials used in the examples and comparative examples is as follows:

[0075] Polyether diol: Polypropylene glycol produced by Shanghai Macklin Biochemical Co., Ltd., with a CAS code of 25322-69-4 and an average molecular weight of 2000;

[0076] Hollow glass microspheres: S22 type sodium calcium borosilicate hollow glass microspheres produced by 3M Company, with an average particle size of 35 μm;

[0077] Liquid crystal polymer fiber: 400D liquid crystal polymer fiber produced by Kuraray Co., Ltd. of Japan Liquid crystal polymer fiber.

[0078] Example 1

[0079] This example provides a preparation method of a hollow glass microsphere-modified polyurethane-based thermal insulation composite material. The hollow glass microspheres are nanoparticles, and the modified polyurethane-based composite material has the function of thermal insulation. The specific preparation method is as follows:

[0080] (1) Preparation of thermoplastic polyurethane:

[0081] The polyether diol is heated to 110 °C and vacuum dehydrated for 2.5 h to remove the moisture in the polyether diol.

[0082] The polyether diol is cooled to 55 °C;

[0083] 4,4'-Diphenylmethane diisocyanate is added to the heated polyether diol, and the molar ratio of 4,4'-diphenylmethane diisocyanate to polyether diol is 2.3:1;

[0084] A catalyst, dibutyltin dilaurate, was added to polyether diol and 4,4'-diphenylmethane diisocyanate. The mass percentage of dibutyltin dilaurate was 3%. Under nitrogen protection, the reaction was stirred for 2.5 h to allow the isocyanate groups of 4,4'-diphenylmethane diisocyanate to fully react with the hydroxyl groups of polyether diol, forming a polyurethane prepolymer.

[0085] Chain extender 1,4-butanediol was added to the polyurethane prepolymer. The reaction temperature between the chain extender 1,4-butanediol and the polyurethane prepolymer was 75 °C, and the reaction time was 1.5 h. The molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer was 1:1, obtaining thermoplastic polyurethane.

[0086] The thermoplastic polyurethane was subjected to plasma treatment. The power of the plasma treatment was 100 W, and the treatment time was 5 min.

[0087] (2) Graft modification of the thermoplastic polyurethane:

[0088] The thermoplastic polyurethane was added to an N,N-dimethylformamide solution of glycidyl methacrylate. The mass fraction of the N,N-dimethylformamide solution of glycidyl methacrylate was 18%, and the mass ratio of glycidyl methacrylate monomer to the thermoplastic polyurethane was 1:18. The reaction was carried out at 55 °C for 8 h to connect the glycidyl methacrylate monomer to the molecular chain of the thermoplastic polyurethane, obtaining a first mixed solution.

[0089] Glycidyl methacrylate and initiator azobisisobutyronitrile were added to the first mixed solution. The mass ratio of glycidyl methacrylate to the thermoplastic polyurethane was 1:18, and the dosage of the initiator was 0.8% of the total mass of glycidyl methacrylate added twice. Under nitrogen protection, the reaction system was heated to 75 °C and stirred for 7 hours to allow the glycidyl methacrylate graft monomer to form branches through double bond reactions, obtaining a second mixed solution.

[0090] The second mixed solution was precipitated and filtered, and the precipitate was washed and dried to obtain the graft-modified thermoplastic polyurethane. The vacuum drying temperature of the thermoplastic polyurethane was 70 °C, and the vacuum drying time was 18 h.

[0091] (3) Pretreatment of hollow glass microspheres:

[0092] The hollow glass microspheres were immersed in a dilute hydrochloric acid solution to remove surface impurities and oxides. The mass fraction of the dilute hydrochloric acid solution was 4%, and the immersion time was 1.5 h.

[0093] The hollow glass microspheres were repeatedly rinsed with deionized water until the rinsing solution became neutral. After filtration, the hollow glass microspheres were dried at 90 °C for 4 h.

[0094] The dried hollow glass microspheres are immersed in an ethanol solution containing silane coupling agent KH560 for 3 hours. Among them, the mass fraction of the silane coupling agent in the ethanol solution of silane coupling agent KH560 is 3%, so that a silane coupling agent coating layer is formed on the surface of the hollow glass microspheres. Then the hollow glass microspheres are taken out and dried at 90 °C for 4 hours to obtain pretreated hollow glass microspheres.

[0095] (4) Preparation of dispersion:

[0096] The graft-modified thermoplastic polyurethane, pretreated hollow glass microspheres and N,N-dimethylformamide are mixed and stirred at 65 °C for 1.5 h to obtain a dispersion. In the dispersion, according to mass parts, the components of each raw material are as follows: 40 parts of graft-modified thermoplastic polyurethane, 100 parts of N,N-dimethylformamide and 10 parts of hollow glass microspheres;

[0097] (5) Coating of dispersion: The dispersion is coated on the liquid crystal polymer fiber by the dipping method, and the coating thickness is about 1.1 mm. After drying, a thermal insulation composite material is obtained. The drying temperature is 100 °C and the drying time is 45 min.

[0098] Example 2

[0099] This example provides a preparation method of a hollow glass microsphere-modified polyurethane-based thermal insulation composite material. The hollow glass microspheres are nanoparticles, and the modified polyurethane-based composite material has the function of thermal insulation. The specific preparation method is as follows:

[0100] (1) Preparation of thermoplastic polyurethane:

[0101] The polyether diol is heated to 100 °C and vacuum dehydrated for 2 h to remove the moisture in the polyether diol.

[0102] The polyether diol is cooled to 50 °C;

[0103] 4,4'-Diphenylmethane diisocyanate is added to the heated polyether diol, and the molar ratio of 4,4'-diphenylmethane diisocyanate to polyether diol is 2.2:1;

[0104] Dibutyltin dilaurate as a catalyst is added to the polyether diol and 4,4'-diphenylmethane diisocyanate. The mass percentage of dibutyltin dilaurate is 1%. Under nitrogen protection, the mixture is stirred and reacted for 2 h to make the isocyanate groups of 4,4'-diphenylmethane diisocyanate react fully with the hydroxyl groups of the polyether diol to form a polyurethane prepolymer.

[0105] Add chain extender 1,4-butanediol to the polyurethane prepolymer. The reaction temperature between the chain extender 1,4-butanediol and the polyurethane prepolymer is 70 °C, the reaction time is 2 h, and the molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer is 0.9:1 to obtain thermoplastic polyurethane;

[0106] Perform plasma treatment on the thermoplastic polyurethane. The power of the plasma treatment is 50 W and the treatment time is 4 min.

[0107] (2) Graft modification of the thermoplastic polyurethane:

[0108] Add the thermoplastic polyurethane to the N,N-dimethylformamide solution of glycidyl methacrylate. The mass fraction of the N,N-dimethylformamide solution of glycidyl methacrylate is 15%, and the mass ratio of the glycidyl methacrylate monomer to the thermoplastic polyurethane is 1:15. React at 50 °C for 10 h to connect the glycidyl methacrylate monomer to the molecular chain of the thermoplastic polyurethane to obtain the first mixed solution;

[0109] Add glycidyl methacrylate and initiator azobisisobutyronitrile to the first mixed solution. The mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15, and the dosage of the initiator is 0.5% of the total mass of glycidyl methacrylate added twice. Under nitrogen protection, heat the reaction system to 70 °C and stir and react for 6 hours to form branches by the double bond reaction of the glycidyl methacrylate graft monomer to obtain the second mixed solution.

[0110] Perform precipitation and filtration on the second mixed solution, wash and dry the precipitate to obtain the graft-modified thermoplastic polyurethane; the vacuum drying temperature of the thermoplastic polyurethane is 60 °C and the vacuum drying time is 12 h.

[0111] (3) Pretreatment of hollow glass microspheres:

[0112] Put the hollow glass microspheres into a dilute hydrochloric acid solution and soak them to remove surface impurities and oxides. The mass fraction of the dilute hydrochloric acid solution is 3% and the soaking time is 2 h;

[0113] Rinse the hollow glass microspheres repeatedly with deionized water until the rinsing solution becomes neutral. After filtration, dry the hollow glass microspheres at 80 °C for 3 h;

[0114] Put the dried hollow glass microspheres into an ethanol solution containing silane coupling agent KH560 and soak for 3 hours. Among them, the mass fraction of the silane coupling agent in the ethanol solution of silane coupling agent KH560 is 2% to form a silane coupling agent coating layer on the surface of the hollow glass microspheres. Take out the hollow glass microspheres and dry them at 80 °C for 5 hours to obtain the pretreated hollow glass microspheres.

[0115] (4) Preparation of dispersion: Mix the graft-modified thermoplastic polyurethane, pretreated hollow glass microspheres, and N,N-dimethylformamide, and stir for 2 h at 60 °C to obtain a dispersion. In the dispersion, according to mass parts, the components of each raw material are as follows: 20 parts of graft-modified thermoplastic polyurethane, 30 parts of N,N-dimethylformamide, and 5 parts of hollow glass microspheres;

[0116] (5) Coating of dispersion: Coat the dispersion on the liquid crystal polymer fiber by the dipping method, with a coating thickness of about 1 mm, and obtain a thermal insulation composite material after drying. The drying temperature is 80 °C and the drying time is 60 min.

[0117] Example 3

[0118] This example provides a preparation method of a hollow glass microsphere-modified polyurethane-based thermal insulation composite material. The hollow glass microspheres are nanoparticles, and the modified polyurethane-based composite material has the function of thermal insulation. The specific preparation method is as follows:

[0119] (1) Preparation of thermoplastic polyurethane:

[0120] Heat the polyether diol to 120 °C and dehydrate it under vacuum for 3 h to remove the moisture in the polyether diol.

[0121] Cool the polyether diol to 60 °C;

[0122] Add 4,4'-diphenylmethane diisocyanate to the heated polyether diol. The molar ratio of 4,4'-diphenylmethane diisocyanate to polyether diol is 2.5:1;

[0123] Add the catalyst dibutyltin dilaurate to the polyether diol and 4,4'-diphenylmethane diisocyanate. The mass percentage of dibutyltin dilaurate is 5%. Under nitrogen protection, stir and react for 3 h to make the isocyanate groups of 4,4'-diphenylmethane diisocyanate react fully with the hydroxyl groups of the polyether diol to form a polyurethane prepolymer.

[0124] Add the chain extender 1,4-butanediol to the polyurethane prepolymer. The reaction temperature of the chain extender 1,4-butanediol and the polyurethane prepolymer is 80 °C, the reaction time is 18 h, and the molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer is 1.1:1 to obtain thermoplastic polyurethane;

[0125] Perform plasma treatment on the thermoplastic polyurethane. The power of the plasma treatment is 200 W and the treatment time is 6 min.

[0126] (2) Graft modification of thermoplastic polyurethane:

[0127] Thermoplastic polyurethane was added to the N,N-dimethylformamide solution of glycidyl methacrylate. The mass fraction of the N,N-dimethylformamide solution of glycidyl methacrylate was 20%. The mass ratio of glycidyl methacrylate monomer to thermoplastic polyurethane was 1:20. The reaction was carried out at 60 °C for 6 h to connect the glycidyl methacrylate monomer to the molecular chain of thermoplastic polyurethane, obtaining a first mixed solution;

[0128] Glycidyl methacrylate and initiator azobisisobutyronitrile were added to the first mixed solution. The mass ratio of glycidyl methacrylate to thermoplastic polyurethane was 1:20. The dosage of the initiator was 1% of the total mass of glycidyl methacrylate added twice. Under nitrogen protection, the reaction system was heated to 80 °C and stirred for 6 hours to form branches by the double bond reaction of glycidyl methacrylate graft monomers, obtaining a second mixed solution.

[0129] The second mixed solution was precipitated and filtered, and the precipitate was washed and dried to obtain graft-modified thermoplastic polyurethane; the vacuum drying temperature of thermoplastic polyurethane was 80 °C and the vacuum drying time was 12 h.

[0130] (3) Pretreatment of hollow glass microspheres:

[0131] The hollow glass microspheres were put into a dilute hydrochloric acid solution for soaking to remove surface impurities and oxides. The mass fraction of the dilute hydrochloric acid solution was 5%, and the soaking time was 1 h;

[0132] The hollow glass microspheres were repeatedly rinsed with deionized water until the rinsing solution became neutral. After filtration, the hollow glass microspheres were dried at 100 °C for 3 h;

[0133] The dried hollow glass microspheres were put into an ethanol solution containing silane coupling agent KH560 for soaking for 3 hours. Among them, the mass fraction of the silane coupling agent in the ethanol solution of silane coupling agent KH560 was 4%, so that a layer of silane coupling agent coating was formed on the surface of the hollow glass microspheres. The hollow glass microspheres were taken out and dried at 100 °C for 3 hours to obtain pretreated hollow glass microspheres.

[0134] (4) Preparation of dispersion: The graft-modified thermoplastic polyurethane, pretreated hollow glass microspheres and N,N-dimethylformamide were mixed and stirred at 70 °C for 1 h to obtain a dispersion. In the dispersion, according to the mass fraction, the components of each raw material were as follows: 60 parts of graft-modified thermoplastic polyurethane, 180 parts of N,N-dimethylformamide and 15 parts of hollow glass microspheres;

[0135] (5) Dispersion coating: The dispersion is coated on the liquid crystal polymer fiber by the dipping method. The coating thickness is about 1.2 mm. After drying, a thermal insulation composite material is obtained. The drying temperature is 120 °C and the drying time is 30 min.

[0136] Comparative Example 1

[0137] This example provides a preparation method of a polyurethane-based composite material. The specific preparation method is as follows:

[0138] 1. Preparation of thermoplastic polyurethane:

[0139] The polyether diol is dehydrated under vacuum at 110 °C for 2 hours to remove moisture. The reaction system is cooled to 50 - 60 °C, and an excessive amount of 4,4'-diphenylmethane diisocyanate is added. The molar ratio of 4,4'-diphenylmethane diisocyanate to polyether diol is 2.3:1. Then, dibutyltin dilaurate with a mass percentage of 3% in the reaction system is added as a catalyst. Under nitrogen protection, the mixture is stirred and reacted for 2 hours to fully react the isocyanate groups with the hydroxyl groups of the polyether diol to form a prepolymer.

[0140] An appropriate amount of the small molecule chain extender 1,4-butanediol is added to the above prepolymer. The molar ratio of the chain extender to the remaining isocyanate groups in the prepolymer is 1:1, and the reaction is continued at 75 °C for 1.5 hours to obtain thermoplastic polyurethane.

[0141] 2. Preparation of dispersion:

[0142] The thermoplastic polyurethane and N,N-dimethylformamide are stirred at 65 °C for 1.5 h to fully dissolve the thermoplastic polyurethane, obtaining a thermoplastic polyurethane resin dispersion.

[0143] Among them, according to the mass parts, the components of each raw material are as follows: 40 parts of thermoplastic polyurethane and 100 parts of N,N-dimethylformamide.

[0144] 3. Dispersion coating:

[0145] The high-modulus liquid crystal polymer fiber fabric is subjected to plasma pretreatment. The thermoplastic polyurethane resin dispersion is uniformly coated on the pretreated liquid crystal polymer fiber fabric and dried at 100 °C for 45 min to obtain a polyurethane-based composite material.

[0146] According to the standards ISO1421 formulated by the International Organization for Standardization, the room temperature tensile strength (N / cm), -30 °C tensile strength (N / cm), and 80 °C tensile strength (N / cm) of the flexible composite materials prepared in Examples 1 - 3 and Comparative Example 1 are tested, and the thermal conductivity (W / (m·K)) is tested according to the standard ISO8301. The test results are shown in Table 1.

[0147] As can be seen from the following table, compared with Comparative Example 1, the thermal conductivity of the thermal insulation composite material in Examples 1-3 is significantly reduced. Therefore, adding hollow glass microspheres to polyurethane effectively improves the thermal insulation performance of the thermal insulation composite material. At the same time, compared with Comparative Example 1, the room temperature tensile strength, -30°C tensile strength, and 80°C tensile strength of the thermal insulation composite material in Examples 1-3 all decrease to varying degrees, indicating that after adding hollow glass microspheres to thermoplastic polyurethane, the flexibility of the thermal insulation composite material under room temperature, low temperature, and high temperature conditions has been effectively improved.

[0148] Table 1: Table of performance indicators for the performance of composite materials

[0149]

[0150] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0151] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention through logical analysis, reasoning, or limited experiments based on the concept of the present invention on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A method for preparing a thermal insulation composite material, characterized in that: The steps include: (1) Preparing thermoplastic polyurethane: using 4,4'-diphenylmethane diisocyanate and polyether diol as raw materials and dibutyltin dilaurate as a catalyst to obtain a polyurethane prepolymer; adding a chain extender 1,4-butanediol to the polyurethane prepolymer to obtain a thermoplastic polyurethane; (2) performing graft modification on the thermoplastic polyurethane: adding the thermoplastic polyurethane to an N,N-dimethylformamide solution of glycidyl methacrylate so that the molecular chain of the thermoplastic polyurethane is connected with the glycidyl methacrylate monomer to obtain a first mixed solution; adding glycidyl methacrylate and an initiator azobisisobutyronitrile to the first mixed solution so that the glycidyl methacrylate grafted monomer forms a branched chain through a double bond reaction to obtain a second mixed solution; precipitating and filtering the second mixed solution, washing and drying the precipitate to obtain a graft-modified thermoplastic polyurethane; (3) Pre-treating the hollow glass microspheres: removing impurities and oxides on the surface of the hollow glass microspheres, and soaking the hollow glass microspheres in an ethanol solution containing a silane coupling agent KH560 for a certain period of time to form a silane coupling agent coating layer on the surface of the hollow glass microspheres, thereby obtaining pre-treated hollow glass microspheres; (4) preparing a dispersion: mixing the graft-modified thermoplastic polyurethane, the pretreated hollow glass microspheres and N,N-dimethylformamide to obtain a dispersion, wherein the components of the raw materials in the dispersion are as follows in terms of weight: 20 to 60 parts of the graft-modified thermoplastic polyurethane, 30 to 180 parts of the N,N-dimethylformamide and 5 to 15 parts of the hollow glass microspheres; (5) Dispersion coating: coating the dispersion on the liquid crystal polymer fiber, and obtaining a thermal insulation composite material after drying.

2. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (1), obtaining the polyurethane prepolymer comprises the following steps: removing moisture from the polyether diol and heating the polyether diol to 50-60° C.; Adding 4,4'-diphenylmethane diisocyanate to the heated polyether diol, wherein the molar ratio of the 4,4'-diphenylmethane diisocyanate to the polyether diol is 2.2 to 2.5:1; Add dibutyltin dilaurate as a catalyst to polyether diol and 4,4'-diphenylmethane diisocyanate, and stir the reaction for 2 to 3 hours under nitrogen protection to allow the isocyanate group of 4,4'-diphenylmethane diisocyanate to fully react with the hydroxyl group of the polyether diol to form a polyurethane prepolymer.

3. The method for preparing a thermal insulation composite material according to claim 2, characterized in that: The process of removing water from the polyether diol comprises the following specific steps: The polyether diol is heated to 100-120° C. and vacuum dehydrated for 2-3 hours.

4. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (1), the reaction temperature of the chain extender 1,4-butanediol and the polyurethane prepolymer is 70-80° C., the reaction time is 1-2 hours, and the molar ratio of the chain extender 1,4-butanediol to the remaining isocyanate groups in the polyurethane prepolymer is 0.9-1.1:

1.

5. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: Before step (2), the method further includes the following specific steps: The thermoplastic polyurethane is subjected to plasma treatment, wherein the power of the plasma treatment is 50-200 W and the treatment time is 4-6 minutes.

6. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (2), when the thermoplastic polyurethane is added to the N,N-dimethylformamide solution of glycidyl methacrylate, the mass ratio of the glycidyl methacrylate to the thermoplastic polyurethane is 1:15 to 1:20, the reaction temperature is 50 to 60° C., and the reaction time is 6 to 10 hours.

7. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (2), glycidyl methacrylate and initiator azobisisobutyronitrile are added to the first mixed solution, the mass ratio of glycidyl methacrylate to the thermoplastic polyurethane is 1:15 to 1:20, and the amount of the initiator is 0.5 to 1% of the total mass of the glycidyl methacrylate added twice.

8. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (2), the vacuum drying temperature of the thermoplastic polyurethane is 60 to 80° C., and the vacuum drying time is 12 to 24 hours.

9. The method for preparing a thermal insulation composite material according to claim 1, characterized in that: In the step (3), the following specific steps are included: The hollow glass microspheres are immersed in a dilute hydrochloric acid solution to remove surface impurities and oxides, wherein the mass fraction of the dilute hydrochloric acid solution is 3-5% and the immersion time is 1-2 hours; The hollow glass microspheres are repeatedly rinsed with deionized water until the rinse solution becomes neutral, and then the hollow glass microspheres are dried at 80-100°C for 3-5h after filtering; The dried hollow glass microspheres are immersed in an ethanol solution containing a silane coupling agent KH560 for a certain period of time, wherein the mass fraction of the silane coupling agent in the ethanol solution of the silane coupling agent KH560 is 2-4%, so that a silane coupling agent coating layer is formed on the surface of the hollow glass microspheres to obtain pretreated hollow glass microspheres.

10. A thermal insulation composite material, characterized in that: The preparation method is described in any one of claims 1 to 9.

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