Thermal insulation composite material and preparation method and application thereof

Abstract

The invention provides a heat insulation composite material which is prepared from the following raw materials in parts by weight: 100 parts of waterborne polyurethane, 10-20 parts of ammonium polyphosphate, 3-8 parts of zinc stannate, 5-15 parts of zinc borate, 5-10 parts of silicon carbide nanowires, 10-20 parts of silicon dioxide aerogel microspheres, 3-5 parts of nano montmorillonite and 2-5 parts of a toughening agent. According to the heat-insulating composite material disclosed by the invention, the balance of environmental friendliness, ultrahigh-temperature stability, low heat conductivity and flexibility is realized through the synergistic effect of multiple components.

Description

Technical Field

[0001] The present invention relates to the field of aerospace technology, and in particular to a thermal insulation composite material and a preparation method and application thereof. Background Art

[0002] Confined detonating cord (CDF) is a key component for detonation transmission in the next-generation aerospace pyrotechnics system. Compared to flexible detonating cord (MDF), CDF is coated with several layers of woven high-strength non-metallic material, resulting in more reliable detonation transmission and a more stable detonation velocity (7000 m / s). Post-detonation, it maintains structural integrity, remains free of rupture and fragmentation, and releases no explosive gases or contaminants. During launch, the detonating cord on the CZ-11's all-solid-fuel launch vehicle must withstand a high-intensity heat flux of 385 kW / m² (equivalent to a temperature of 2000°C) from the engine. This thermal environment is even more severe than that of China's liquid-fuel Long March series of launch vehicles. During flight, the rocket's intermittent ignition, startup, and launch are primarily controlled by the onboard detonating cord. Failure to meet thermal protection requirements for the detonating cord could lead to launch failures. Quartz composite hose for restrictive detonating cord plays an important role in transient harsh environments.

[0003] Chinese patent CN202011284422.8 discloses a heat-proof / insulating composite material, its preparation method and application. The composite material includes the following components in parts by weight: 90-110 parts of polyurethane, 5-25 parts of ammonium polyphosphate (APP), 1-10 parts of zinc oxide, 2-15 parts of antimony oxide, 3-20 parts of perlite, 5-20 parts of zinc borate, and 5-20 parts of ammonium borate. The heat-proof / insulating composite material provided by the present invention has performance advantages that are incomparable to traditional heat-proof materials, and has the advantages of low thermal conductivity, high thermal insulation, light weight, good flexibility, cold resistance, heat resistance, convenient process implementation, and high reliability. The restrictive detonating cord hose containing the composite material can block the transfer of heat within a certain period of time, and plays an important role in transient harsh environments. This patent has the following disadvantages: (1) Antimony oxide (Sb2O3) as a flame retardant synergist can improve flame retardancy, but it has bioaccumulative toxicity and is not in line with modern environmental protection trends; (2) The solvent cyclohexanone: a volatile organic compound (VOC), is not friendly to worker health and the environment; (3) Although perlite can insulate, it has low density and is easy to pulverize, and may become ineffective under long-term high temperature; and its high-temperature stability is insufficient. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention discloses a thermal insulation composite material which achieves a balance among environmental protection, ultra-high temperature stability, low thermal conductivity and flexibility through the synergistic effect of multiple components.

[0005] One of the objectives of the present invention is to provide a thermal insulation composite material.

[0006] A second object of the present invention is to provide a method for preparing the thermal insulation composite material.

[0007] A third object of the present invention is to provide application of the thermal insulation composite material in the aerospace field.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0009] A thermal insulation composite material is prepared from the following raw materials in parts by weight:

[0010] 100 parts of waterborne polyurethane, 10-20 parts of ammonium polyphosphate, 3-8 parts of zinc stannate, 5-15 parts of zinc borate, 5-10 parts of silicon carbide nanowires, 10-20 parts of silica aerogel microspheres, 3-5 parts of nano-montmorillonite, and 2-5 parts of toughening agent.

[0011] The waterborne polyurethane index requirements are as follows: solid content 40-50%, viscosity 100-1000mPa.s, preferably Yantai Wanhua 1675. Waterborne polyurethane, as an environmentally friendly adhesive, provides flexibility and film-forming properties. It has good compatibility with APP, facilitating the uniform dispersion of the intumescent flame retardant system. The waterborne system avoids VOC release and forms an intercalated structure with nano-montmorillonite, enhancing barrier properties.

[0012] The ammonium polyphosphate has a degree of polymerization of 1500 to 2000 and a solubility of less than 0.1 g / 100 mL of water at 25° C., preferably Exolit AP462 produced by Clariant of Germany. The ammonium polyphosphate decomposes upon heating to generate polyphosphoric acid and ammonia, forming an expanded carbon layer; and reacts with zinc borate to generate a borophosphate glass layer, which enhances the stability of the carbon layer and provides flame retardancy and smoke suppression.

[0013] At high temperatures, zinc stannate reacts with the decomposition products of ammonium polyphosphate to form tin-phosphorus oxide, which covers the surface of the material and isolates it from oxygen. Together with silicon carbide nanowires, this enhances the high-temperature stability of the carbon layer, preventing it from collapsing at temperatures up to 3000°C.

[0014] When zinc borate is heated, it first releases water vapor, which absorbs a significant amount of heat, lowering the ambient temperature. Zinc borate reacts with ammonium polyphosphate to form a borophosphate glass layer, which suppresses smoke and toxic gases. It also works with silica aerogel to reduce smoke density during combustion, while the aerogel absorbs smoke particles.

[0015] If the zinc stannate dosage is too low, the zinc borate and ammonium polyphosphate will form an excessive borophosphate glass layer, which will soften the carbon layer at high temperatures and reduce heat resistance. If the zinc stannate dosage is too high, the resulting tin-phosphorus oxide layer will be too thick, which will inhibit the expansion effect of ammonium polyphosphate and reduce flame retardancy. Preferably, the weight ratio of zinc stannate to zinc borate in the composite material is 1:1.5-1:2.5.

[0016] The silicon carbide nanowires, with a diameter of 50-100 nm, form a three-dimensional network skeleton at high temperatures (above 2000°C), preventing cracking or collapse of the carbon layer. This improves the uniformity of the material's thermal conductivity and avoids localized overheating. They can also be combined with the expanded carbon layer of ammonium polyphosphate to form a "honeycomb-skeleton" composite structure, combining flexibility and high-temperature resistance.

[0017] Silica aerogel microspheres serve as thermal insulation. Their nanoporous structure (porosity >90%) reflects thermal radiation and blocks heat conduction (thermal conductivity ≤0.02W / m·K). Combined with the nano-montmorillonite layer structure, they create a "maze effect," extending the heat path. The aerogel's lightweight properties offset the increased density of the silicon carbide nanowires.

[0018] Nano-montmorillonite has a lamellar structure that migrates to the surface of the material during combustion, forming a dense barrier layer that slows the diffusion of combustible gases. Intercalated with waterborne polyurethane, it enhances the mechanical strength and flame retardancy of the matrix. The nano-montmorillonite is preferably Nanomer 1.28E from Sigma-Aldrich (USA).

[0019] The toughening agent is preferably an epoxy-based hyperbranched polymer, which increases the material's elongation at break (≥50%) through molecular chain entanglement and hydrogen bonding. It forms a "rigid-flexible" network with the silicon carbide nanowires, balancing flexibility with high-temperature strength. The epoxy-based hyperbranched polymer is preferably Boltorn E1, an epoxy-functionalized hyperbranched polyester from Perstorp Polyols AB of Sweden.

[0020] The present invention also includes the use of the thermal insulation composite material in a hose for a restrictive detonating cord, and the specific use method includes the following steps:

[0021] (1) Mix waterborne polyurethane with deionized water (solid content adjusted to 40%) and stir until uniform;

[0022] (2) adding ammonium polyphosphate, zinc stannate, and zinc borate in sequence and dispersing by high-speed shearing;

[0023] (3) adding silicon carbide nanowires, silica aerogel microspheres, nano-montmorillonite and toughening agent, and ultrasonically treating to ensure no agglomeration;

[0024] (4) The mixed slurry is coated on the surface of the quartz hose and dried and solidified at 100-250°C to form a coating with a thickness of 0.3±0.05mm.

[0025] The beneficial effects of the present invention are as follows:

[0026] Through the synergistic effect of multiple components in four dimensions: chemical flame retardancy, physical insulation, high-temperature stability and mechanical flexibility, effective blocking of instantaneous ultra-high temperature (3000°C level) heat flow is achieved, while meeting the stringent requirements of aerospace detonating cord for lightweight, flexibility and environmental stability. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0028] The raw materials involved in the embodiments and comparative examples are as follows:

[0029] The waterborne polyurethane is from Yantai Wanhua 1675; the ammonium polyphosphate is Exolit AP462 produced by Clariant; the nano-montmorillonite is Nanomer 1.28E produced by Sigma-Aldrich of the United States; the toughening agent is an epoxy hyperbranched polymer, which is the epoxy-functionalized hyperbranched polyester Boltorn E1 produced by Perstorp Polyols AB of Sweden; the silica aerogel microspheres are purchased from Nanomate New Material Technology Co., Ltd.; the silicon carbide nanowires are purchased from ENO MATERIAL brand silicon carbide nanowires provided by Qinhuangdao Yinuo High-tech Materials Development Co., Ltd., with the brand name SF-1.

[0030] The formulation compositions of Examples 1-3 are shown in Table 1.

[0031] Table 1

[0032]

[0033]

[0034] The preparation and use methods of the above Examples 1-3 are as follows:

[0035] Preparation method

[0036] (1) Mix waterborne polyurethane with deionized water (solid content adjusted to 40%) and stir until uniform;

[0037] (2) Add ammonium polyphosphate, zinc stannate, and zinc borate in sequence and disperse at high speed (3000 rpm, 30 min);

[0038] (3) Silicon carbide nanowires, silica aerogel microspheres, nano-montmorillonite, and toughening agent were added and ultrasonicated (40 kHz, 20 min) to ensure no agglomeration;

[0039] (4) The mixed slurry is coated on the surface of the quartz hose and dried and solidified at 150°C to form a coating with a thickness of 0.3±0.05 mm.

[0040] The performance test results of Examples 1-3 are shown in Table 2.

[0041] Table 2

[0042]

[0043] The formula of Comparative Example 1-2 is the same as that of Example 2, and the total amount of zinc stannate and zinc borate is also the same as that of Example 2, except that the ratio of zinc stannate: zinc borate is modified. The specific use effects are shown in Table 3.

[0044] Table 3

[0045]

[0046] From Table 2-3, it can be seen that the ratio of zinc stannate to zinc borate = 1:2 in Example 2 is the current optimal solution, which has the characteristics of flame retardancy, low smoke, high temperature stability and mechanical integrity, and meets the extreme protection requirements of aerospace detonating cord.

[0047] The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced with equivalents, without departing from the spirit and substance of the claims of the present invention; and such modifications or replacements remain within the scope of the claims of the present invention.

Claims

1. A thermal insulation composite material, characterized in that: In parts by weight, it is prepared from the following raw materials: 100 parts of waterborne polyurethane, 10-20 parts of ammonium polyphosphate, 3-8 parts of zinc stannate, 5-15 parts of zinc borate, 5-10 parts of silicon carbide nanowires, 10-20 parts of silica aerogel microspheres, 3-5 parts of nano-montmorillonite, and 2-5 parts of toughening agent.

2. The thermal insulation composite material according to claim 1, characterized in that: The waterborne polyurethane has the following index requirements: solid content 40-50%, viscosity 100-1000 mPa.s.

3. The thermal insulation composite material according to claim 1, characterized in that: The polymerization degree of the ammonium polyphosphate is 1500-2000.

4. The thermal insulation composite material according to claim 1, characterized in that: The weight ratio of the zinc stannate to the zinc borate is 1:1.5-1:2.

5.

5. The thermal insulation composite material according to claim 1, characterized in that: The silicon carbide nanowire has a diameter of 50-100 nm.

6. The thermal insulation composite material according to claim 1, characterized in that: The toughening agent is an epoxy hyperbranched polymer.

7. The use of the thermal insulation composite material in aerospace detonating cord according to claim 1, characterized in that: The specific usage includes the following steps: (1) Mix waterborne polyurethane with deionized water, adjust the solid content to 35-45%, and stir until uniform; (2) adding ammonium polyphosphate, zinc stannate, and zinc borate in sequence and dispersing by high-speed shearing; (3) adding silicon carbide nanowires, silica aerogel microspheres, nano-montmorillonite and toughening agent, and ultrasonically treating to ensure no agglomeration; (4) Apply the mixed slurry on the surface of the quartz hose and dry it at 100-250°C to form a coating.

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